Chapter XI: Part II: Marine Invertebrates (6)

As the hermit grows he is occasionally obliged to find a new or larger shell, and there are amusing anecdotes of the troubles he experiences at these times while house-hunting. Very often he tries several shells before he finds one to fit. There is a tradition, not, however, well authenticated, that if the shell chosen happens to be occupied by its natural owner, the crab tears out and devours the unfortunate occupant. If the desired shell is occupied by another hermit inferior in strength to himself, he proceeds to take possession by violence. He then examines carefully the empty shell, inserting his legs and feelers, and if he decides to occupy it he withdraws his abdomen from the old shell and darts it so quickly into the new one that the act of transference is difficult to follow. After walking about with the new shell it sometimes proves to be unsatisfactory and further search becomes necessary. After it is well domiciled the crab never ventures outside the shell until it is obliged to change again on account of growth, or because some stronger crab dispossesses him. The shells of hermit-crabs serve frequently as the home of other animals which live with them a commensal life. The hydroid /Hydractinia polyclina/ often covers the exterior of such shells with a brown, velvety growth. Some sea-anemones also are commensals [pg267] with hermits. /Adamsia palliata/ is always found on the shell occupied by /Eupagurus prideaux/, and never on any other. This is a European form. On our own coast a red anemone, the /Epizoanthus americanus/, found in deep water off the entire eastern shore, fastens on the shell occupied by the hermits /Eupagurus pubescens/ and /E. kroyeri/. This anemone in time absorbs the shell of its host and itself becomes its protector--an advantage to the hermit, who finds room in the yielding polyp-mass for its increasing size, and feels no longer the necessity for change of domicile. The female hermit holds its eggs in the posterior feet until they are hatched; the young are then released, pass into the water, and soon find shells for themselves.

GENUS ^Pagurus^

^P. bernhardus.^ This is a large species, bright red in color,
rough and hairy. It inhabits the shells of /Fulgur carica/ or
of /Polynices heros/. It ranges from Cape Cod northward, and is
replaced on the northern California coast by /P. alaskensis/ and
/P. aleuticus/.

^P. pollicaris.^ This hermit inhabits shells similar to those
occupied by the last, but is pale red in color, and its surface
is granulated and not hairy. The short joint of the chela has a
broad angle. It ranges from Massachusetts to Florida, and occurs at
low-water mark on rocky and shelly bottoms of bays and sounds.

^P. longicarpus.^ A quick-moving little hermit with long chelipeds,
found in small shells at the water's edge in quiet places. They
exist in great numbers and are eaten, shell and all, by fish. This
species can be distinguished from all others by its very light
color and metallic luster.

GENUS ^Clibanarius^

^C. vittatus.^ This hermit is found from North Carolina southward
along the edge of the water and in tide-pools. It cannot be
mistaken [pg268] for any other hermit common on our coast, since
it has the very distinctive feature of white longitudinal stripes
on the ambulatory feet. The chelipeds are about equal, rough with
tubercles, and the tips have smooth black edges. Body and feet are
quite hairy. The color is brown and white.

GENUS ^Pylopagurus^

This genus is represented in Southern waters by several species. One of the most characteristic of them lives in /Dentalium/, the tooth-shell. The outer surface of the right hand is formed to close the shell. All the ambulatory feet and the very small left hand fold beneath, leaving only the flat surface of one hand exposed to view. Another species lives in a shell covered with polyzoans.

FAMILY ~CENOBITIDAE~

GENUS ^Cenobita^

^C. diogenes.^ This large hermit-crab, found in Florida and in more
southern waters, inhabits the beautiful pearly shell of /Livona
pica/. It lives on land a part of the year, but spends the breeding
season in the water. It can be distinguished by its land-roaming
habits, its large left cheliped, very stout walking-legs, and
compressed eye-stalks. This species climbs the hills, but is more
frequently met with in low, shaded, marshy places. (Plate LIX.)

FAMILY ~HIPPIDAE~

GENUS ^Hippa^

^H. talpoida.^ This animal, commonly known as the "sand-bug,"
differs greatly in appearance from a crab. When the appendages are
folded under the carapace it somewhat resembles an egg, the body
being ovate, about half as broad as long, and the sides forming a
nearly regular curve. The carapace is about one and a half inches
long, convex, yellowish-white, and nearly smooth. The abdomen is
long and pressed under the body, reaching nearly to the front.
The eyes are minute and on the ends of long, slender stalks. The
antennae are plume-like and about as long as the carapace. /Hippa/
lives on sandy beaches at or near low-water mark, exposed to the
action of the waves. It burrows with great rapidity into the loose
and shifting sands, using the short and stout second, third, and
fourth thoracic legs and the appendages of the sixth abdominal
segment [pg269] for pushing and digging. Crabs of this species
are gregarious and may be seen in great numbers, though but few
will be captured together by digging, as they rapidly disappear
beneath the sand. Sometimes they are found swimming about in the
tide-pools. They seem to live upon the organic particles contained
in the sand, which they swallow, the mouth not being adapted for
mastication. This species ranges from Cape Cod to Florida. (Plate
LXI.)

^H. analoga.^ Similar to /H. talpoida/, but broader and flatter. It
is bluish above, yellowish-white below, and the fringing hairs are
black. Found on the California coast.

GENUS ^Albunaea^

^A. gibbesii.^ This animal is found with /Hippa/, and, like it,
burrows rapidly in the sand. Its general outline is square. The
surface of the carapace is marked off with denticulated lines,
which make the back appear as if composed of plates. The front edge
of the carapace has a row of teeth and a prominent spine at the
anterior angles. The abdomen is doubled under itself (not fitting
into a groove of the thorax, as in ordinary crabs), this animal
being intermediate between the long- and the short-tailed forms.
The eyes are on triangular, plate-like stalks. The antennules are
very long and are fringed with hair. The chelipeds have claw-like
joints, which close across the straight, broad end of the hand.
The first two pairs of walking-feet have curious sickle-like
terminal joints. The animal is about one and a quarter inches long.
/Albunaea/ does not extend as far north as /Hippa/, its range being
from Georgia southward. (Plate LXI.)

FAMILY ~PORCELLANIDAE~

The crabs of this family are little more than one quarter to one half of an inch across the back. The chelipeds are broad and flattened. The first three pairs of walking-legs are well developed, and the fifth pair are very small and are doubled over the base of the carapace. The sixth segment of the abdomen has a pair of biramous appendages, which, with the telson, form a swimming-fan.

GENUS ^Porcellana^

^P. sayana.^ Carapace little longer than broad; breadth about one
quarter of an inch; smooth; has three acute denticulations between
the eyes, the middle one the largest and depressed in the center;
two denticulations on each anterior side; chelae fringed with hair
on the edges; walking-legs somewhat hairy; fifth pair of legs
folded over base of carapace; color reddish, with white spots.
This species was once called /occulata/, because of the eye-like
spots over its entire surface. The posterior part and abdomen have
longitudinal bands of color. The claws are marked like the shell.
Found from South Carolina southward, often in the shells inhabited
by hermit-crabs. (Plate LXI.) [pg270]

GENUS ^Petrolisthes^

^P. sexspinosus.^ Carapace longer than broad; breadth about one
half of an inch; space between the eyes broad, but not divided into
three teeth as in /Porcellana sayana/; second joint of the cheliped
has five broad teeth on its front edge and five or six small
spines on its outer edge; fifth pair of legs doubled over base of
carapace; whole body traversed with broken red lines. Found from
South Carolina southward. (Plate LXI.)

^P. armatus.^ Carapace longer than broad; breadth about one
quarter of an inch; prominent and wide between the eyes; a small
sharp spine on each anterior side; chelipeds long; second joint
of cheliped twice as long as broad, with three teeth on the front
edge and four or five small spines on the outer edge. Found on the
Florida coast. (Plate LXI.)

FAMILY ~LITHODIDAE~

The species of this family have a broad, ovate, uneven body and a prominent rostrum. The fifth pair of legs are rudimentary and are folded under the carapace in the branchial chambers, so that the crabs appear to have but four legs on each side. This is the distinguishing feature of the family, and makes them easily recognized.

GENUS ^Lithodes^

^L. maia.^ The carapace is cordate (heart-shaped), and longer than
broad, exclusive of the rostrum. The margin is recurved all around,
and is beset with numerous very long spines. Six spines on each
anterior side margin are regular and longer than the others. The
surface of the carapace is covered with tubercles and spines and
elevated in places. The rostrum is spiny, a third as long as the
carapace, and has two spines at the base, one above the other,
a spine at each side, two lateral spines near the middle, and
two terminal divergent spines. The chelipeds are unequal and are
covered with spines, those on the inner margin being the longer.
The color is yellowish-red, lighter underneath; the spines are
darker. Found on the fishing-banks off the coast of Maine. (Plate
LXI.)

GENUS ^Echidnocerus^

^E. cibarius.^ This curious crab has the carapace raised in front
into a large cone-like elevation terminating in a long point. Three
prominent but smaller cones extend across the center of the back,
and two still smaller ones occur on the posterior sides and in the
middle of the posterior margin. The whole surface of the carapace
is covered with coarse granulations arranged in rosette-like
groups. The chelipeds and legs are beset with large tubercles and
fold together in such a manner that when retracted the crab is a
close, compact, box-like mass, with a very rough, [pg271] spiny
armature. The antennae are broad at the base and covered with small
spines on the sides and upper surface, and the eye-stalks are also
spiny. This crab sometimes attains the size of ten inches across
the carapace and a weight of seven pounds, being among the largest
crabs known. It is found at the mouth of the Columbia River and
along the northwest coast. (Plate LXII.)

^E. foriminatus.^ This species resembles /E. cibarius/ in the
manner of closing the feet, forming a compact, box-like, spiny
armature. The body is more depressed than that of the latter,
and the cone-like elevations on the back are less prominent. The
spines are hairy. The characteristic feature of this species is a
semicircular cut in the second joints of the chelipeds, directly
opposite to similar depressions in the first walking-legs, so that
when the feet are folded a round hole is left, through which water
flows freely to the gill-openings, which might, without these open
holes, be obstructed by the close folding of the legs against the
carapace. Found off the California coast near San Francisco. (Plate
LXII.)

GENUS ^Acantholithodes^

^A. hispidus.^ The whole body in this species, including the legs,
is covered with hairy spines. The abdomen is broad, and covers
about the whole under surface of the body, and is also beset with
hairy spines, but they are less prominent than those on the upper
side. The rostrum, terminating in spines, reaches to the tips of
the eye-stalks, which are also spiny. The chelipeds are larger and
longer than the walking-feet; the latter taper to a point, ending
in a sharp nail. The shape of the body resembles somewhat that of
a toad. This is a deep-water species, but it is sometimes brought
ashore at Monterey, California, by fishermen who find it in the
stomachs of fishes.

GENUS ^Cryptolithodes^

^C. sitchensis.^ The most striking characteristic of this singular
species is the great development of the carapace, which forms
a broad, thin shield extending beyond the body and legs, and
completely hiding the animal beneath it. The carapace is smooth
and uneven, has a high ridge through the center of the anterior
part, and the sides are broadly expanded and bluntly pointed at the
extremity. The rostrum appears like a small rectangular piece cut
out of the anterior side of the carapace. This species is found in
the Strait of Fuca. A similar species, /C. typicus/, is found near
low-water mark on the surf-washed rocks of the beach at Monterey,
California. (Plate LXII.)

GENUS ^Phyllolithodes^

^P. papillosus.^ The carapace is triangular, about two inches
wide at the base, and narrowing to a long, pointed rostrum which
terminates in a forked spine. The surface of the carapace is deeply
depressed in parts, and forms a heart-shaped figure in the center.
The lateral margins have four prominent spines on each side, the
two at the posterior ends being [pg272] thicker than the other
two. The abdomen is broad, covering the whole under side of the
body, and is marked off with prominent raised ridges diverging from
the center line. The legs are all beset with long, rough spines.
Habitat, the northwest coast. Taken from the stomachs of fishes off
Monterey, California. (Plate LXII.)

SUBORDER ~BRACHYURA~

THE CRABS

This group contains the true crabs, which are the highest of the /Crustacea/. In form they are quite the reverse of the first group. In the /Macrura/--except in the anomalous forms--the body is long and cylindrical and the abdomen extended, but in the /Brachyura/ the body is flat and broad and the abdomen short and reflexed. Crabs of this suborder inhabit all seas of the globe, and are found from the shore to great depths. Some species live on land, some on the shore, some in deep water. Some forms burrow in the sand; others live under stones and boulders, or conceal themselves in crevices of rocks or in the cavities of sponges. They are divided into many families, and creep, climb, swim, or burrow, their structure being modified to their respective modes of life. There is also great variation in their shapes as well as in their color and markings. This diversity is so great and peculiar that it seems as though each one were more curious than the others.

In crabs the cephalothorax is depressed and often broader than long. The abdomen is relatively small and is folded under the thorax, lying in a groove which it fits so perfectly as to be quite hidden from above. The appendages of the abdomen are much reduced in number. The male has two pairs; the female has four pairs, which it uses for carrying its eggs. The first pair of walking-legs are comparatively large, and end in chelae, or pinching-claws. The other eight legs terminate in simple points, except in the swimming varieties, when the fifth pair is flattened to form fins, or swimming-paddles. The eye-stalks are long and fit into sockets on the carapace. Both pairs of feelers are small. The antennules are frequently folded into small grooves. The external or third pair of maxillipeds are broad and flat, and cover the mouth-parts like a lid, or operculum. [pg273]

Crabs, like other crustaceans, are scavengers, living on dead animal matter; but the land species are also vegetarian in diet. They are great fighters, but are also wily, often averting danger by resorting to stratagem. They are an interesting and curious group, as they possess a good degree of intelligence and have amusing habits.

From the time they leave the egg until they attain the adult form they pass through several complete and singular metamorphoses. The most marked forms are called the /Zoea/ and the /Megalops/. So little do these resemble the adult that originally they were classed as distinct genera far removed from the one to which they really belong. After the larva has moulted several times it appears as in the illustration on page 248--the last zoea stage. From this it changes directly to /Megalops/; the /Zoea/, seeming to be attacked with violent convulsions, wriggles out of its skin a full /Megalops/ (page 248). The animal then has enormous eyes, an extended abdomen, an elongated carapace, and swimming-legs. This stage is a short one, and at the first moulting changes to a form nearly approaching the adult. From this time they grow by shedding the shell at certain periods. This shedding is supposed to occur twice each summer until they have reached full growth, after which it is probable that they do not again moult; for often they are found with extraneous organisms, such as barnacles and sponges, upon them, of a size that must have required a considerable period of time for growth. The sexes of the same species sometimes differ so much that it is difficult to classify them. Even naturalists have been led into the error of assigning the male and female to separate species.

The front side margins of the carapace in many crabs are edged with a row of teeth or with spines, which vary in number and character in different species. In the spider-crabs the whole surface of the carapace is generally studded with tubercles, spines, and stiff hairs of a peculiar character. This armature is for protective purposes, and is often used to secure foreign bodies, such as algae, hydroids, and polyzoans, which the crabs place upon their backs to disguise themselves. The burrowing crabs are usually smooth. When in motion the crab moves sideways, using the legs [pg274] of one side to pull with and those of the other side to push with. As all the legs do not move at the same time, a continuous and uniform motion is kept up. Some species move with great rapidity, notably the sand-crab, /Ocypoda arenaria/. Often when pursued they will run into the surf instead of to their holes. The common edible crab, /Callinectes sapidus/, of the Atlantic coast, the fiddler-crabs, and the spider-crabs are among the well-known representatives of /Brachyura/.

FAMILY ~PORTUNIDAE~

SWIMMING CRABS

GENUS ^Carcinides^

^C. maenas^ (M. J. Rathbun), ^Carcinus maenas^ (Leach), the green
crab. This is one of the most common species on the Atlantic coast
from Cape Cod to New Jersey, and is very abundant in Vineyard
Sound, Buzzard's Bay, and Long Island Sound. It is found between
tide-marks, frequently well up on the beach, hiding under loose
stones, also in tide-pools and in holes and cavernous places on
the shore. It is from one and a half to two inches long, and a
little more in breadth. It has five acute teeth on each side of the
anterior part of the carapace. Its color is green, spotted with
yellow, making it quite conspicuous. The surface of the carapace
and limbs is more or less granulated. The posterior feet are
flattened to form swimming-paddles. It is a very lively creature
and has reckless audacity when brought to bay, which justifies its
specific name (which implies frenzy). The French call it /crabe
enrage/. [pg275]

GENUS ^Callinectes^

^C. sapidus^ (Mary J. Rathbun), ^C. hastatus^ (Stimpson), the blue
crab. This is the common edible crab of the Atlantic coast. It is
known at the North as the "blue crab," and at the South as the
"sea-crab." It is found from Cape Cod to Florida, and after the
lobster is the crustacean which has the greatest commercial value,
being taken in immense quantities for the markets, not only when
the shell is hard, but immediately after moulting, before the new
shell has hardened, when it is known as the "soft-shelled crab."
It inhabits muddy shores, and is common in bays and at the mouths
of estuaries. The carapace is about twice as broad as it is long,
and has a long, sharp spine on each side which projects outward.
This is a distinguishing feature. There are eight short spines on
each side between the long spines and the eyes; then come recesses
for the eyes, and between the eyes are four unequal teeth and a
small spine underneath. The chelae are large and somewhat unequal
in size; then come three pairs of simple feet and a fifth pair,
which are flattened, forming swimming-organs. The margins of the
carapace and abdomen are fringed with fine hairs, as are also most
of the joints of the limbs. The upper surface of the body and claws
is dark green in color, the lower surface is dingy white, the feet
blue, and the tips of the spines reddish. The body is compressed,
the carapace being moderately convex above, and is covered with
minute granulations, which are more numerous over some portions
than over others. The abdomen of the female is very broad and fills
the entire space between the bases of the posterior pair of feet.
During the spawning season it is so charged with eggs that often
it projects out almost at right angles with the carapace. The
[pg276] crabs of this species are very active and can swim rapidly.
They also have the habit of pushing themselves backward into the
mud for concealment. They are predaceous and pugnacious, and have
great strength in their claws, which they use with dexterity.
They not only fight their own kind, but show a bold front to all
enemies, including man. The average size is six inches across the
carapace.

GENUS ^Ovalipes^

^O. ocellatus^ (Rathbun), ^Platyonichus ocellatus^ (Latreille),
the lady-crab or sand-crab. A species common on sandy shores from
Cape Cod to Florida. It is found among the loose sands at low-water
mark, even on the most exposed beaches, and also is abundant on
sandy bottoms offshore. At low-water mark it buries itself up
to the eyes and antennae in the sand, where it watches for prey
and foes, and quickly disappears beneath the sand when danger
approaches. It possesses the power of burrowing in common with
other marine animals which inhabit exposed beaches of loose sand.
By burying itself deep in the sand it is protected from the action
of the breakers. This species is easily distinguished by the color
and shape of its carapace, taken in connection with its posterior
swimming-feet. The body is nearly as long as it is broad, with
five prominent spines on each side. The front margin is indented
on each side of a three-spined rostrum, to form cavities for the
eyes. The first limbs are large and have claws; the posterior ones
are flattened into swimming-feet, and the intermediate three pairs
are simple in structure, ending in points. In color it is white,
covered with spotted rings of red and purple. [pg277]

WALKING CRABS

FAMILY ~CANCROIDAE~

GENUS ^Cancer^

^C. irroratus^, the rock-crab. This is the common crab of the New
England coast. It ranges from Labrador to South Carolina, but is
rare south of New Jersey. It is found on sandy as well as on rocky
shores at and below low-water mark and also between tide-marks,
hiding among rocks, nearly buried in sand or gravel, and in
tide-pools, where sometimes amusing combats between the males may
be seen. The carapace is suboval, one third broader than long,
the breadth being often from three to four inches. The surface is
granulated but smooth; the color is yellowish, closely dotted with
brown. The eyes are on short stalks in deep, circular holes, and
between the eyes are small teeth. There are nine blunt teeth along
each side of the front edge of the carapace. The first pair of legs
are short and stout, and terminate in claws. The four posterior
pairs are slender and end in pointed tips. This is an edible crab,
and it is devoured by the larger fishes, but does not--although
there seems to be no reason for it--share to any extent a place in
the markets with the blue crab, /Callinectes sapidus/.

^C. borealis^, the Jonah crab. This crab resembles, and is
frequently taken for, /C. irroratus/. It is larger than the latter
in full growth, and is heavier and more massive. The carapace and
claws are rougher, the granules being irregular in size. The legs
are proportionately shorter and heavier. The teeth on the anterior
margins are rounded in front, but the posterior ones are sharply
pointed. In color [pg278] it is brick-red above and yellowish
beneath. It inhabits rocky shores only and is found at low tide on
the surface of the rocks, where it is exposed to the action of the
waves and also to the attacks of birds of prey, which feed upon
it, while /C. irroratus/, concealed under the rocks in the same
locality, escapes their depredations. This species is supplied to
the Newport market, where it is considered preferable to the blue
crab. Its range is from the eastern end of Long Island to Nova
Scotia.

^C. magister.^ This species inhabits the Pacific coast and ranges
from Alaska to Lower California. The adult male is from seven to
nine inches broad and from four to five inches long. The anterior
margin of the carapace is an almost regular elliptical curve with
nine small teeth on each side. At the end of the curve a large,
pointed tooth projects directly outward, and from this the carapace
slopes abruptly backward, giving a narrow posterior end. The
surface of the carapace is undulated and covered with papillae, and
is light reddish-brown, shading to lighter color in the back. The
color of the legs and under surface of the animal is yellowish.
The claws are toothed above and ribbed at the sides. It inhabits
sandy bottoms below tide-mark and is the largest and most important
edible crab of the western coast.

^C. productus^, the red crab. This species, like the preceding one,
is of large size and inhabits the western coast from Alaska to
the Gulf of California. The carapace is four and a half inches in
length, from five to seven in breadth, and somewhat elliptical in
outline. The teeth on the anterior margin are distinctly separate
in the adult, but in the young appear as wrinklings of the edge
of the carapace. The posterior margins are concave. In color the
animal is dark red above and yellowish beneath in the adults, but
variable in the young, sometimes being yellow spotted with red,
or banded with red and yellow. It inhabits rocky shores. This is
an edible crab, but is not taken for the markets, /C. magister/
supplying all demands. [pg279]

[pg280]

^C. antennarius^, the rock-crab of the Pacific coast. This
species of the California coast inhabits rocky bottoms below
low-water mark. The carapace is three and a half inches long by
five or six inches wide, and dark purplish-brown in color. The
chelae are marbled with purplish spots and are nearly smooth. The
distinguishing features of this crab are its large and hairy
antennae, the hirsute margins of its abdomen and walking-feet, and
the numerous hairs on the under side of its body.

GENUS ^Menippe^

^M. mercenaria^, the stone-crab. This species lives in deep holes
in the mud along the borders of creeks and estuaries, and also
in crevices between fragments of rock, in stone-heaps and other
debris, and is found from South Carolina to Texas. These crabs are
edible, and in some localities are hunted for food, one manner
of capturing them being to thrust the hand and arm into their
holes and drag them out, an operation attended with danger to the
inexperienced hunter, who is likely to be badly pinched. They are
withdrawn with difficulty, as they offer a strong resistance,
bracing themselves with their claws against the sides of their
holes, and often hold so firmly to the rocks that they are torn
[pg281] apart. They are also taken by a hooked iron which is thrust
into the hole; the crab seizes it and is then suddenly jerked from
its hole. The adult measures about three by four and a half inches,
and the body is from one inch to two inches thick. One of the chelae
is larger than the other, and both are proportionately enormously
large, and are tipped with black. The terminal joints of the other
four pairs of legs are thickly fringed with hairs and end in points
which seem like nails.

FORMER GENUS ^Panopeus^

^Eupanopeus herbstii^, ^Eurypanopeus depressus^, ^Neopanopeus
texana^, ^Rhithropanopeus harrisii^ (Mary J. Rathbun). These four
species, formerly all called /Panopeus/, are small crabs which live
in the mud and are commonly known as mud-crabs. They are abundant
under stones in muddy places, and occur on the Atlantic coast from
Massachusetts Bay to Florida, though they are not commonly met with
north of New Jersey. /Eupanopeus herbstii/ is the largest one of
the group, some of the Southern ones measuring two inches across.
It is found living in mud at low-water mark, or burrowing in banks
near high-tide mark. It is dark olive-brown, the claws broadly
tipped with black. /Eurypanopeus depressus/ is flattened above,
and is smaller than /Neopanopeus texana/, which is somewhat convex
above. The last two are commonly found together and have similar
habits. /Rhithropanopeus harrisii/ lives near high-water mark and
also in salt-marshes, and is comparatively rare. The claws lack the
dark tips of /E. herbstii/, and a distinct groove follows the edge
of the carapace.

FAMILY ~GRAPSIDAE~

GENUS ^Hemigrapsus^

^H. nudus^ (Mary J. Rathbun), ^Heterograpsus nudus^ (Stimpson);
^H. oregonensis^ (Mary J. Rathbun), ^Heterograpsus oregonensis^
(Stimpson). These two species, commonly called respectively the
/purple shore-crab/ and the /yellow shore-crab/, are the most
abundant species of the California coast. Hundreds may be found
congregated under a single rock. They range from Sitka to Lower
California. /H. oregonensis/ literally swarms in sloughs of salt
or brackish water, and hundreds of uplifted threatening claws
confront the intruder who ventures on these mud-flats when the tide
is out. This species, the yellow shore-crab, has a nearly square
body. The anterior half of the side margins has two rather deep
indentations, [pg282] making two spine-like projections which bend
forward. The four posterior pairs of legs are more or less hairy;
the chelae are rather large in proportion. The male is about one
inch across and the female is one third less in size. The general
color is yellow. /H. nudus/ is found in the same localities, and
differs from /H. oregonensis/ in being purple in color, with
mottled claws, and in having the denticulations less pronounced
and the walking-feet devoid of hairs. It is also a little larger.
(Plate LXIII.)

GENUS ^Pacygrapsus^

^P. crassipes.^ A species very common on the California coast south
of San Francisco. This crab is similar in general features to the
purple and yellow ones described above, but is considerably larger,
and the carapace is banded with color.

FAMILY ~OCYPODIDAE~

GENUS ^Ocypoda^

^O. arenaria^, the sand- or ghost-crab. The name /Ocypoda/ means
"swift-footed," and, as it implies, this species is especially
noted for its rapidity of movement. These crabs are the opposite
of the strong-armed, thick-shelled, slow-moving /Cancroidae/. An
instance is told of a collector having great difficulty to keep up
at full run with one which he chased for a considerable distance
over the sand. They are also dexterous in burrowing, and live in
holes, often three feet deep, dug perpendicularly into the sand.
They wander far from their burrows when the tide is out, and
every little while raise their stalked eyes and stand on tiptoe
to look about. If alarmed, they run with great rapidity to the
nearest burrow, or, if danger is close, press themselves on the
sand until an attempt is made to touch them, when they again dart
away rapidly, and in running hold their bodies high, and double
and dodge so that it is difficult to catch them. /Ocypoda/ is
colored almost exactly like the sand, and this mimicry, together
with its fleetness, makes it interesting to note and difficult
to capture. It inhabits sandy beaches above tide-mark from Long
Island to Brazil, and subsists largely upon the beach-fleas, which
inhabit the same localities. It springs upon them, very much as a
cat catches a mouse. The carapace of this species is almost square
in outline, and on the anterior corners ends in a spine. A small
portion of the carapace folds down like a band between the eyes. On
each side of this band, and extending across the front, are large
grooves for the eye-stalks. The body is about an inch thick; the
first joints of the chelae are toothed; one chela is a little longer
than the other, and both are coarsely granulated. The other four
pairs of legs are thickly fringed with hairs. (Plate LXIII.)

GENUS ^Uca^

^U. minax^ (^Gelasimus minax^), ^U. pugnax^ (^Gelasimus pugnax^),
^U. pugilator^ (^Gelasimus pugilator^), the fiddler-crabs. These
species [pg283] of fiddler-crabs occur on the Atlantic
coast. They congregate in immense numbers, and excavate their
holes in convenient localities above the reach of the tides--on
salt-marshes, far up the estuaries, and along the mouths of rivers,
even where the water is quite fresh. The males have one claw very
largely developed; the other chela is small. The former is likened
to a fiddle, the latter to a bow, and this, together with the
waving motion of the large claw, gives them their popular name.
This comparatively enormous claw is a distinguishing feature by
which they are easily recognized without other description. The
female has claws of small and equal size. These crabs burrow holes
in the mud or sand half an inch to two inches in diameter and a
foot or more in depth. The upper part is nearly perpendicular,
becoming horizontal below, with a chamber at the end. One species,
/U. minax/, constructs an archway over the mouth of its burrow, in
which it sits and surveys the surroundings, but quickly retreats
when danger approaches. The crab makes its burrow by scraping up
the mud or sand and forming it into pellets, which it carries under
the three anterior walking-feet on the under side, using the legs
on the side moving forward, and the fourth one on the other side,
to climb out of the hole. After peering cautiously about, the
crab emerges, and carries its load four or five feet away before
dropping it; then again looks about before quickly running back;
and, finally, turning its stalked eyes, looks in all directions
and suddenly disappears, soon to return with another load. The
burrows cover considerable areas, and the crabs are so abundant
that the marshes and shores sometimes seem to be alive with them.
When alarmed, they lift the large claw and run sideways, after
the manner of all crabs, to their holes, and, as many are likely
to retreat into the most convenient one, the owner often finds
his burrow occupied by other tenants, whom he unceremoniously
proceeds to pull out. /U. minax/ ranges from southern New England
to Florida, and lives on salt-marshes farther away from the sea
than the others, and often where the water is quite fresh. It
is larger than the other species, and can be distinguished by a
red patch at the joints of the legs. It is a vegetarian in diet,
living on small algae. This is the species which constructs a little
observation-house over the mouth of its burrow. It can live out of
water, and without food, for several days. /U. pugilator/ lives
on sandy and muddy flats and beaches near high-water mark, where
the sand is compact and somewhat sheltered, and ranges from Cape
Cod to Florida. This species, like /U. minax/, is a vegetarian.
/U. pugnax/ is exceedingly abundant on muddy banks and ditches of
salt-marshes, the banks being sometimes completely honeycombed and
undermined by them. It ranges from Cape Cod to Florida. [pg284]

FAMILY ~MAIIDAE~

The members of this family are known as "spider-crabs." Their bodies are thick and more or less round in form, narrowing in front to a long, beak-like projection. The surface is generally rough and irregular, having tubercles, spines, prickles, and hairs. The legs are long. These crabs are often covered with seaweeds, hydroids, and other organisms, which they gather with their long and flexible chelipeds and place upon their backs, presumably to conceal themselves from their enemies. They seem to select, instinctively or with reason, such things as will bear transplanting, sometimes using sponges and polyps which are not destroyed by being torn apart, and they also select their dress with reference to its masking uses. A /Hyas/ covered with bright-colored algae was seen to remove them and replace them with sponges, when transferred to the locality of the latter, where the former did not grow. The animal takes in his claw the object he has gathered, and first holds it to his mouth, where it is moistened with a secretion of mucus or cement, and then places it on his back. If it does not hold, the operation is repeated, often several times, a new spot on the shell being selected each time. It has also been found that the coats of these crabs are covered with hairs which are differently arranged in different genera, some being hooked, others serrated, etc., and that these aid in holding the transplanted organisms in place. The crab is sometimes so covered with these growths as to be entirely concealed beneath them. It is a sluggish animal, and inhabits shallow water along the whole of the Atlantic and Pacific coasts.

GENUS ^Libinia^

^L. dubia^, ^L. emarginata^. These two species inhabit the
Atlantic coast, and are found on muddy shores and flats, among
decaying seaweed, in eel-grass, and even beneath the surface of
the mud. They are covered with hairs, and sometimes have planted
on their backs algae, hydroids, and even barnacles. The legs of /L.
emarginata/ often spread a foot or more. The males are much larger
than the females. The species ranges from Maine to Florida. /L.
dubia/ does not extend north of Cape Cod. It is found more commonly
than /L. emarginata/ in very shallow water [pg285] near shore. It
is not so thickly covered with spines, and has a longer rostrum,
which is also more deeply divided at the end. (Plate LXIII.)

GENUS ^Hyas^

^H. coarctatus^, the toad-crab. This species of spider-crab is
found from Greenland to New Jersey, in shallow as well as in deep
water. Its body resembles strongly, both in form and size, that of
a toad, hence its common name. It forms an important part of the
food of the cod.

^H. lyratus.^ A toad-crab of the Pacific coast, ranging from Bering
Sea to Puget Sound; named from the lyre-shape of its carapace.

^H. araneus.^ A species which especially resembles a toad in its
form. Found off the northern New England coast. (Plate LXIII.)

GENUS ^Loxorhynchus^

^L. crispatus^, the sheep-crab. This crab occurs on the coast of
southern California. The body is thick and about three inches
across the widest portion, and tapers to a long, prominent rostrum.
It is covered with long tubercles and spines and with short,
bristly hairs; the legs are long, the chelipeds stretching fully
two feet.

GENUS ^Pugettia^

^P. gracilis.^ A small spider-crab found on the Pacific coast from
Alaska to Puget Sound. Its body is one half of an inch wide and
[pg286] one inch long, with prominent spines on the sides of the
carapace, which narrows in front into a long beak ending in two
spines. It is red and green above, red beneath. (Plate LXIII.)

GENUS ^Sternorhynchus^

^S. sagittarius.^ This is one of the most delicately formed of the
spider-crabs. The body has narrow longitudinal stripes of light and
dark color. It lives offshore from Cape Hatteras southward.

GENUS ^Epialtus^

^E. productus^, the kelp-crab. This crab inhabits the coasts of
California and Oregon, and is found among seaweeds on rocks just
below low-water mark. The carapace is smooth, is quadrate in form,
is about two inches long and broad, has two spines on each side,
and has a prominent denticulated rostrum. This is the most common
spider-crab of the Pacific (California) coast. It is olive-green,
thus simulating in color the kelp among which it lives. (See page
285.)

GENUS ^Pitho^

^P. aculeata.^ The carapace has six spines on each side, the
middle two being sometimes partly united; the general outline is
pentagonal; the length about one inch. Quite common on the Florida
coast. (Plate LXIII.)

GENUS ^Lambrus^

^L. pourtalesii^, the long-armed spider-crab. The carapace is
broader than it is long and has three elevations all covered with
spines. The general surface is pitted and granulated; the rostrum
points downward; the chelipeds are very long, the margins armed
with spines; the breadth of the carapace is about one and a half
inches; and the length of the chelipeds is about three and a half
inches. Its range is from Cape Cod to Florida, and it lives among
the rocks. (Plate LXIV.) [pg287]

FAMILY ~CALAPPIDAE~

GENUS ^Calappa^

^C. flamma^, the box-crab. This singular animal lives on sandy and
muddy bottoms offshore, from North Carolina southward. The carapace
is broad and straight on the posterior side, and is curved on the
anterior side, narrowing to the front. The posterior side has
prominent denticulations. The body is one and a half inches thick,
about four to five inches wide, and two to three inches long.
The chelae are large, broad, and flattened, and are so arranged
that when flexed they fit closely together across the front. When
folded, and the small legs are withdrawn under the carapace, the
animal is shut up as if in a box, and resembles a shell. When in
danger it closes its doors, as it were, and abandons itself to the
waves, which often carry it ashore. The crested claws resemble the
head of a cock. (Plate LXIV.)

FAMILY ~PINNOTHERIIDAE~

GENUS ^Pinnotheres^

^P. ostreum^, the oyster-crab. The female of this species lives
in the gill-cavity of the oyster, and is particularly abundant in
oysters from the Chesapeake. The males are seldom seen, and rarely
occur in the oyster, but swim freely about. They are smaller than
the female, have a firmer shell, and are dark brown above, with a
dorsal stripe and two conspicuous spots. The under side of the legs
is whitish. The female is commensal, at least in the adult form,
and its thin, whitish, transparent carapace is tinged with pink.
The species ^P. maculatum^ lives in /Mytilus edulis/ (mussel) and
in the smooth scallop, /Pecten magellanicus/. The oyster-crab is a
true messmate, and its presence in the oyster may be advantageous
in helping to provide food for its host. This crab, like the rest,
holds its eggs in the posterior feet until hatched, when the larvae
leave the parent and swim about for a while. The females, at the
megalops stage, enter oysters--sometimes two enter the same oyster,
but seldom more than one; there it remains permanently, growing to
the size of an inch or more in diameter, and becomes a degenerate.
The eyes become smaller; the shell never hardens, like its allies
which live in open water; its limbs and chelae are weak; and it has
no pugnacity, the protection afforded by the oyster doing away with
the need for the common protective features of its kind. /Pinnixa
cylindrica/, a related species, lives in the tubes of large annelid
worms as a commensal. [pg288]

ORDER =STOMATOPODA=

GENUS ^Squilla^

^S. empusa.^ This animal suggests somewhat the lobster, though very
unlike it. The carapace is much smaller and softer, and leaves
the last three segments of the thorax uncovered. The abdomen is
larger and longer in proportion, while the legs and organs are
quite different. The whole body is depressed, instead of laterally
compressed. It measures from eight to ten inches in length and two
inches in breadth. Instead of chelae, the last joint of the great
claw has six sharp curved spines, which fit into sockets in a
groove on the second joint. By this singular organ they hold their
prey securely. The abdominal feet carry the gills. The antennal
scales are oblong and fringed with hair. The antennules terminate
in three flagella. The caudal appendages and telson are long,
strong, and armed with spines. This animal lives in burrows in the
mud below low-water mark, forming large, irregular holes, but is
frequently washed ashore. In color it is pale yellowish-green, each
segment being bordered with darker green and edged with yellow. It
is found from Cape Cod to Florida.

ORDER =CUMACEA=

GENUS ^Diastylis^

^D. quadrispinosus.^ Among the minute /Crustacea/ which swim on the
surface of the water, this species, with other small forms, may be
captured by using a muslin net. It is a quarter of an inch or less
in length. It is easily distinguished by its large carapace, the
posterior portion of which is marked off in transverse ridges, the
anterior end running into a sharp-pointed rostrum. It has a long,
slender abdomen, the sections of which [pg289] are distinctly
marked, and it terminates in long, forked spines, which are longer
than the telson. It is found from New Jersey northward.

ORDER =ARTHROSTRACA=

SUBORDER ~AMPHIPODA~

The /Amphipoda/ have a laterally compressed body, with gills on the thoracic feet and an elongated abdomen. The segments of the thorax are not united, nor covered by a carapace, but the whole body is covered with a segmented, polished, flexible cuticle. The three anterior legs of the abdomen are for swimming-feet, and the posterior ones are adapted for springing. The antennae are long and hairy. The amphipods comprise the beach-fleas and many other small crustaceans which abound between tide-marks on all beaches. Besides serving in no small measure as food for fishes, they are scavengers of the beach, and consume large quantities of waste matter. They are sometimes used in preparing skeletons for anatomical specimens. Animals to be skeletonized, being fastened to boards and anchored just below the surface of the water in sheltered places, are divested of all flesh in a few hours, and the bones are more completely cleaned than if prepared by a naturalist.

GENUS ^Orchestia^

^O. agilis^, the beach-flea. These little crustaceans exist in
countless numbers under the masses of sea-wrack on the beach. When
disturbed they jump about with great agility by means of the last
three pairs of abdominal feet, which are adapted to this purpose.
In color the animal is brown and much resembles the decaying
seaweeds among which it lives and upon which it probably feeds. The
antennules are short, the antennae long, on two long, jointed bases.
The second pair of feet in the males terminate in chelae. The last
abdominal appendages are stiff and pointed backward. The abdomen is
curved under. The length of /Orchestia/ is half an inch or less.
Some species occur on all beaches. /O. agilis/ ranges from New
Jersey to Greenland.

GENUS ^Talorchestia^

^T. longicornis^ (^Talitrus longicornis^). This species is similar
to Orchestia agilis, but is about an inch long when mature and
of a paler [pg290] color. It jumps like the latter, but not so
strongly. It is found among the weeds and burrowing in the sand
a little below high-water mark. The wet sand is often completely
filled with its holes. It can be distinguished by its very long
antennae. Another species, ^T. megalophthalma,^ is distinguished by
its shorter antennae and very large eyes. Both of these species are
grayish in color and closely resemble the sand. Found from Cape Cod
to New Jersey.

GENUS ^Gammarus^

^G. locusta.^ The animals of this genus are among the largest of
the amphipods. The males are larger than the females, sometimes
being one and a half inches long. They are abundant under stones
and /Fucus/ at and near low-water mark. Although much larger than
the beach-fleas, they otherwise resemble them. They do not jump
like the former, but move rapidly, lying on the side, and in water
swim with the back downward. Two pairs of the thoracic feet are
chelate, and three pairs are longer than the others. The feet
on the last segments of the abdomen are stiff and turn sharply
back, forming a part of the tail, which is used most effectively
in locomotion. The antennules and antennae are of about the same
length. Several species of /Gammarus/ occur in the same range, all
having the same general characteristics; some have but one pair of
chelate feet; the antennules are usually shorter than the antennae;
the females of all the species have no chelate feet. /G. locusta/
ranges from New Jersey to Greenland. The color is generally
reddish- or olive-brown. ^G. annulatus^ is found in the same
places, but usually a little higher up on the beach; it is lighter
in color, and has dark bands with red spots on the sides of the
abdomen. ^G. mucronatus^ occurs from Cape Cod to Florida. ^Melita
nitida^ is a smaller slate-colored amphipod found in some places;
another is ^M[oe]ra levis^, which is whitish, with black eyes.

GENUS ^Chelura^

^C. terebrans^, the boring amphipod. This little crustacean
is associated in its work on submerged timber with the isopod
/Limnoria lignorum/. The excavations of the latter are narrow and
cylindrical, running down into the wood, while /Chelura/ makes
larger burrows in oblique lines near the surface, which give the
wood the appearance of having been plowed. It is very active and
destructive. It feeds upon the wood into which it burrows. Its
color is semi-translucent, thickly mottled above with pink. [pg291]

GENUS ^Caprella^

^C. geometrica.^ These very curious little animals, which are so
slender as to seem like skeletons, are found in abundance clinging
to hydroids, /Polyzoa/, delicate algae, or eel-grass, or under
stones in tide-pools. They resemble in color, and often in form,
the objects on which they live. Holding on by the posterior feet,
they extend the body out rigidly or sway it about, so that they
resemble little sticks or branches, and often escape detection. In
walking, they bring the hind feet up to the front ones, doubling
the body into a loop like the canker- or measuring-worm. The
appendages on the anterior and posterior ends are furnished with
chelae and hooks; those of the middle section are rudimentary. This
animal cannot be mistaken for any other. /C. geometrica/ is found
from Cape Cod to North Carolina. Some of the species of this genus
may be found on every coast.

SUBORDER ~ISOPODA~

The isopods have an elongate, flattened, but more or less arched body, composed of seven thoracic segments and a short abdomen of six segments. The six segments of the abdomen are smaller than those of the thorax, and are often more or less united, sometimes into a single piece with scarcely any trace of division above; but the number of pairs of appendages is generally six, showing the composite nature of the apparently simple organ. The last segment, or telson, is broad and has a pair of modified appendages. The seven thoracic legs are not all equal, as the name would imply, but vary greatly in different species. As a rule, they are adapted to walking or attachment, and in the female some have delicate plates which form brood-pouches. The swimming-feet fold under the abdomen, and in some species are inclosed by the first pair, which are large and plate-like, and form a complete cover for the others. The isopods are a large and widely distributed order, varying in size, and are inconspicuous because they cling closely to objects. They are retiring in habit, though extremely ferocious.

The sow-bugs or pill-bugs, common in gardens, under leaves in the woods, and under almost any pile of rubbish among decaying vegetable matter, are a land species of isopods. Other species inhabit [pg292] ponds and streams of fresh water, and still others are found along the shores of all oceans, abounding among the marine vegetation of the shallow waters. Some swim free in the open sea; others are brought up from the greatest depths. Others, again, are parasites, and live in the internal organs of fishes and prawns. Sometimes a prawn is found having what appears like a very swollen throat, which actually is a little parasitic isopod of the family /Bopyridae/ attached to its gills.

GENUS ^Cirolana^

^C. concharum.^ The body consists of fourteen segments, the first
being the head, the next seven the thorax, and the last six the
abdomen. On the head are the triangular eyes, the antennules, and
the antennae, and underneath is the mouth, which is covered by the
maxillipeds. The dorsal surface is more or less rounded. At the
bases of all the segmental thoracic rings excepting the first one
are sutures marking off square, scale-like pieces (/epimera/). The
epimera form a border to the side margins. The legs are attached to
the epimera, which are, in fact, the upper segments of the legs.
The first three pairs of legs have a general resemblance to one
another, and are directed forward. The last four pairs are much
longer and flatter, and are directed backward. The telson, or last
segment, is triangular, and the square or blunt apex is fringed
with hairs. On the ventral surface of the thorax in the adult
females there is a long pouch for the reception and development
of the eggs. This species is usually about one and a half inches
in length, but sometimes is longer. Its color is yellowish, with
a brown edge on the posterior margins of the segments, somewhat
translucent in the thinner parts. It is found from Cape Cod to
South Carolina, swimming about in shallow water, and is especially
abundant in winter.