S16 
FOREST AND STREAM. 
[Oct. 14, 1905. 
settles itself into the sand or mud at the bottom of the" 
hole and waits until the rising tide offers an opportunity 
to move about again. 
The blue crab has verj^ seldom been seen to come out 
on land voluntarily, although it is able to sustain life for 
several hours when removed from the water. In low, 
swampy situations I have occasionally seen an individual 
moving about in the dense grass or hanging to the grass 
just above the water, and in Miss Rathbun’s paper. “The 
Genus Callinectes,” there is a description by Mr. Willard 
Nye, Jr., of the migration of a large number of crabs 
from a small pond to the ocean over a beach 4CK) feet 
wide. They had been imprisoned in the shallow water 
and were forced by cold weather to make the excursion 
to deeper places. 
During the molting, periods the crab will always hide 
itself, if possible, under some submerged timber, rock, or 
bunch ff s- i" ", Here it will remain quietly until after 
its shell has been shed and the new shell has hardened. , 
The color of the crab is more or less variable, and^at 
is believed' by the fishermen that the animal is able to 
change its hue slightly to approximate the color of its 
surroundings. Light grayish-green individuals are said 
to be taken on sandy bottoms, while the dark olive-green 
are said to be found among thb grass. This theory, hovv^ 
ever, is not ver}^ well borne out by crabs held in captivity 
in the live boxes, for there they retain their original 
color-s, and even after they have cast their shells exhibit 
quite as much variety as before. 
Food. 
Ihe blue crab’s food is of a varied character, but the 
animal is pre-eminently a scavenger and a cannibal. In 
the shallow waters of ponds and small tidal streams it 
preys to a certain extent upon small fish, which it stalks 
with some cunning and seizes by a quick movement of 
its large claws. In such situations, too, I have sometimes 
observed it nibbling at the tender shoots of eel grass or 
other aquatic vegetation, or picking at the decayed wood 
of some sunken log. Its favorite food, however, is the 
flesh of some dead and putrid animal, to obtain which it 
will travel a considerable distance from its hiding place. 
A piece of stale meat or a rotten fish will attract the crabs 
for several yards around, and they will swarm over the 
morsel until it is entirely devoured. The offal from 
stables and water closets which project over the water 
furnishes the crabs with many a meal, and in such spots 
numbers of the animals rnay be observed lying in wait for 
food. 
Wherever crabs are abundant they constitute a source 
of great annoyance to fishermen, for they are adepts at 
stealing bait from the hooks, and will return time and 
again after having been drawn to the surface of the water 
and apparently frightened away. 
An injured crab, if thrown into the water, will be 
speedily set upon by its associates and torn to pieces. 
Even one that is uninjured, if small or in the soft-shelled 
condition, is likely tO’ be captured and eaten by stronger 
individuals. 
In eating a bit of food the crab first grasps it in the 
large claws and pushes it back under the front of the 
shell, where it is seized between the tips of the second 
pair of legs and pushed forward and upward to a point 
where it can pass between the third maxillipeds to the 
jaws. These strong organs masticate the food while the 
other mouth-parts prevent the escape of the smaller par- 
ticles. It is then swallowed and the complicated set of 
teeth in the stomach reduce it to a thin fluid mass before 
it is allowed to pass into the intestine. 
Digestion in the crab seems to be a rapid process, for 
the food disappears so quickly from the stomach that this 
organ is usually found to be perfectly empty within a few 
minutes after having received a full meal. It is a com- 
mon idea among the fishermen that food is not retained 
in the crab’s stomach at all, but this I have, disproved by 
numerous dissections. . 
Reproduction. 
The sexes of the crab are separate, and reproduction is 
effected by means of eggs, which are laid by the female 
after copulation. 
Crabs may be found pairing at almost any time during 
warm weather, but there seem to be five or six periods 
between early June and the beginning of cold weather, 
when the act is at its height. During these times mated 
crabs, “doublers,” as they are called by the fishermen, are 
found in considerable numbers, either lying on the bottom 
in shallow water or swimming at the surface. It appears 
that the male crab is able tO' distinguish the female which 
is about to shed her shell, and having found such a one, 
seizes her and carries her about with him, sometimes for 
a day or two, until the shedding of her shell is imminent. 
He then places her in some sheltered place and stands 
guard over her ready to repel the advances of any other 
male. At this time the female invariably is of the virgin 
form, and copulation has not taken place. When_ she 
sheds her shell, however, she has passed into the oviger- 
ous form, the broad semi-circular abdomen of her new 
condition having been withdrawn from the shell of the 
narrow triangular abdomen of the virgin form. She is 
now ready for copulation, and is immediately approached 
again by her mate. When the female is: ready, to produce 
her eggs for this act it seems that she seeks the ocean or 
the mouth of some large bay. In Chesapeake Bay mating 
crabs are abundant at least as far north as Annapolis, but 
a crab with eg.gs is very seldom found there. On the 
other hand, at Cape Charles City, Va., at Hampton, Va., 
and neighboring points, egg-bearing females are far more 
abundant than either males Or virgin females during the 
latter part of summer, but apparently do- not often come, 
into shallow water. 
The eggs of a crab are very minute, about one-one -hun- 
dredths of: an inch in diameter, and they -are very nqmer-* 
ovts. ’ it ^havinl: been estimated that a single female m 4 y 
ptodu^e' as many as 3,000,000. As soon as the eggs are 
laid they adhere to the fringes of hairs on the swimmerets 
and form a mass which is nearly a third- as large as ihe 
female’s body. ‘ They are carried about thus until they 
hatch, '.when the young, after clinging to the mother for 
a short time, loosen their hold and begin a free existence. 
Molting. 
and any change of form occurs not gradually and con- 
tinuously, but suddenly and at intervals, and is always 
.precedccl by the ca.sting off of the confining skin or shell, 
-a process known as molting or eedysis. 
As the crab approaches the shedding period it begins 
-tq show its condition by various external “signs,” which 
are' well known to the fishermen and are of great im- 
portance to them. The first indication is a narrow white 
line which appears just within the thin margin of the last 
two joints of the posterior pair of legs. This line is so 
,n.arrcw and so obscured as to be barely visible, but it is 
immediately detected by the expert, and the individual 
bearing it is classed as a “fat crab,” or more vulgarly as 
a “snot.” Within three or four days the white line gives 
way to an equally narrow and obscure red line, and a set 
of fine white wrinkles makes its appearance on the blue 
skin between the wrist (carpus) and the upper arm 
„ (meros). Such a crab is known as a “peeler,” and may 
be confidently expected to cast its shell within a few 
hours. As the time progresses the marks become more 
and-' more evident, and a reddish color (especially in vir- 
gin females) begins to appear at the margins of the seg- 
,ments of the abdomen. Then, on the under surface of the 
carapace, extending from the neighborhood of the mouth 
■ abound the sides and backward to the posterior margin, 
there appears a narrow fracture, so that the whole upper 
surface of the shell can be raised up from the back like 
a lid, to expose the soft body beneath. Such a crab is 
termed a “shedder” or a “buster.” At this time the ani- 
mal usually lies motionless, but if disturbed is still cap- 
'able of movement, and may crawl or swim slowly away. 
It is incapable of showing any great muscular force, how- 
ever, and -can inflict only an insignificant pinch with its 
claws. 
- The actual casting of the shell is now a matter of only 
a few minutes ; a quarter of an hour will usually suffice, 
though the operation may be prolonged to- three or four 
times that period if the crab is disturbed or if it is suffer- 
in'g from some recent injury. In the latter case it is often 
• unable to complete the process and dies. By convulsive, 
throbbing movements the hinder pair of legs begin to- be 
withdrawn from their encasement and are finally freed. 
Meanwhile, the other legs have been started out and the 
body has begun to protrude more and more from the 
shell. At last everything is out except the front of the 
body and the large claws, but the latter, on account of the 
great discrepancy between their size and that of the 
narrow articulations through which they must be with- 
drawn, require some further effort before they can be 
freed. The thing would hardly be possible at all were it 
not for the fact t’nat on the upper surface of the, large 
segment of the arm (meros) a broad triangular surface 
of the shell becomes loosened and rises up like a flap to 
make way for the crowded tissues within. Some of the 
hard shell of the other lower (proximal) segments also 
seems to- become softened and elastic, so that by a steady 
pull the great pincers are finally drawn through. Thus 
the crab has backed out of its shell and meanwhile it has 
grown, for if it is caught and measured it will be found 
to be considerably larger than it was before. 
The skin is soft and the animal looks and feels flabby 
and helpless. The back is wrinkled, and the “horns,” or 
large lateral spines, are curled curiously forward. Within 
a few minutes, however, the body fills out, the horns 
straighten, and the growth at this interval is complete. 
The crab is- now known as a “soft-shell,” and from the 
ffisthetid standpoint is at the height of its glory, for all 
the brilliant coloration of the various parts is un- 
dimmed by any of the shell deposits, the soft integument 
seeming to bear the bright pigments at the very surface. 
Under natural conditions the crab usually selects some 
place of concealment in which to pass the period of shed- 
ding, and probably does not leave it until the new shell 
has hardened, but it is by no means helpless, even imme- 
diately after eedysis has occurred. On the tips of legs 
which seem too soft to support any weight whatever it 
can walk away, or, if forced to make the effort, can swim. 
The new shell hardens quickly. Within twelve hours it 
becomes parchment-like and the crab is called a “buckler,” 
“buckram,” or a “bucklum”; in two or three days it is as 
hard as ever and once more starts out in search of food.* 
Aatotomy. 
Autotomy, or the automatic throwing off of the ap- 
pendages, is very characteristically shown in the blue 
crab and is of frequeiat occurrence. Very often if a large 
individual, in the- hard-shelled condition, is captured and 
held by one leg it will snap the limb off and make its 
escape. Likewise, if one of the legs is injured toward 
the tip the entire member will be dropped off. The break- 
age always occurs at the same point — across one of the 
segments near the. base of the leg — and is a provision of 
nature to prevent the animal from bleeding to death. It 
is practiced ordinarily only by the hard-shelled crabs; an 
injury to a soft-shelled individual usually causes death. 
Under other conditions, however — notably, a sudden low- 
ering of temperature — the act has been observed, and in 
one of the early attempts to procure soft crabs for mar- 
ket, by confining the hard crabs in an inclosure until they 
had shed their shells, severe cold weather reduced the 
entire catch to a lot of legless bodies (“buffaloes,” they 
are called by the fishermen). 
Autotomy seems to be limited to the legs, for, so far 
as I have iaecn able to- determine, none of the other ap- 
pendages are ever thrown off, although if they are for- 
cibly remoAmd they will be regenerated. 
Regeneration of the parts cast off usually follows auto- 
tomy. but, according to the researches of several biolo- 
gists: will not take place indefinitely. Three or four times 
.seems to be the limit. The process of regeneration is 
quite rapid. At the. first molt after a limb has been cast 
off^ provided that the injury does not occur immediately 
' betore a molt, the new limb, appears as a small bud in 
^ which all the missing segments may be found, coiled in 
an' elongate- spiral. At the next molt the segments 
straighten out and the new limb, except for its smaller 
size, looks like the one which was cast off. Another molt, 
■; possibly two, will be sufficient to restore the limb to its 
f full size. . 
*It is believed by the fishermen that the molting of . the crabs 
• is influenced largely by the moon and the tides, but the evidence 
to support this theory is very contradictory. 
The Blue Crab, 
BY W. P. HAY, M.S., PROFESSOR OF BIOLOGY, HOWARD UNI- 
VERSITY. 
(Appendix to the Report of the Commissioner of Fisheries.) 
The following report embodies the results of two 
surnmers’ work (1902 and 1903) in the crab-producing 
region bordering Chesapeake Bay. The information was 
gathered incidentally in connection with a thorough study 
of- the diamond-back terrapin, and on that account is by 
no means as complete as could be desired. Many of the 
theories advanced by the fishermen and packers regarding 
the blue crab have not yet been subjected to close exam- 
ination, although every opportunity has been taken for this 
purpose. In some cases the reports secured were so con- 
tradictory that it is not deemed safe to express an opinion 
concerning them. Quite a number of facts, however, have 
been brought to light, and they are here presented in the 
hope that they may prove valuable to those engaged in 
the fishery or to those whose duty it is to secure the 
enactment of laws to regulate and prolong it. 
Distfifaation and Habitat. 
. The natural range of the blue crab is from Massachu- 
kets Bay to some, as yet undetermined point on the east 
coast of South America. On the coast of the United 
States it is common from Cape Cod to the southern ex- 
tremity of Texas, and throughout the greater portion of 
this long coast line' it is very abundant. Its favorite habi- 
tat is in the waters of some bay or at the mouth of a 
river, and it seems to prefer shallow water to that of 
much depth. Consequently, such bodies of water as Dela- 
ware Bay, Chesapeake Bay, and the protected channels 
along the coasts of Virginia and other South Atlantic 
and Gulf States, fairly swarm with these creatures. Chesa- 
peake Bay is especially favorable and has long been 
famous, not only for the great number of crabs which it 
produces, but also for their large size and exceptionally 
fine flavor. 
■ Although the blue crab is essentially an inhabitant of 
salt water, it is frequently found in water that is only 
slightly brackish or even apparently quite fresh. Speci- 
mens have been recorded from the Hudson River as far 
north as Newb-urg, and on creditable authority I have 
learned of the presence of an occasional individual in the 
Potomac River and the Eastern Branch opposite the city 
of Washington. At Crisfield, Md., and at other points 
along both the eastern and western shores of Chesapeake 
Bay, I have frequently observed the blue crab in ponds 
and ditches, often at a distance of a mile or two from the 
bay and in water that was nearly fresh. 
Power of Movement. 
Either in the water or on land the blue crab is an ani- 
mal . of great activity and has considerable power of 
endurance. Progression through the water is effected by 
means of a sculling motion of the broad, oar-like pos- 
terior legs, and under ordinary conditions is slow, the 
effort of the animal being apparently only to keep itself 
afloat while it is borne along by the current. Under these 
conditions the movement is either backward or sidewise. 
The shell is held with the posterior portion uppermost, 
the legs are brought together above the back and strike 
backward and downward at the rate of from twenty to 
forty strokes per minute. When alarmed, however, the 
animal strikes out with great vigor and rapidity, moving 
its paddles too swiftly for the eye to follow; it moves 
through the w-'ater alm.ost as rapidly as a fish and quickly 
sinks below the surface. When on the bottom and undis- 
turbed, the crab may be seen to- walk slowly about on the 
tips of the second, third and fourth pairs of legs, the large 
pincers being held either extended or folded close under 
the shell and the paddles either raised and resting against 
the back of the shell or assisting the movement by slow 
sculling strokes. In such cases the movement is in any 
direction — forw^ard, backward or sidewise — although the 
usual direction is sidewise. If the animal beconies 
alarmed it moves away by a combination of the walking 
and swimming motions and often disappears like a flash. 
In fact, so rapid is the movement that it is almost im- 
possible to see how it is accomplished. It is too steady 
and uniform to be a series of leaps, and the animal seems 
too far above the bottom to be running upon it; yet all 
the legs are in motion except the large first pair. Of the 
latter, the one on the side toward which the animal is 
moving is held straight out sidewise, while the other is 
folded under the shell. 
Method of Concealment. 
The coloration of the crab is such as to harmonize very 
perfectly with the. surroundings, and the anirnal attempts 
ver_y little concealment if there are other objects on the 
bottom. Often, however, a clear, sandy bottom or some 
oozy pond will be found to be almost alive with crabs 
which have buried themselves until only their eyes and 
the antennae are exposed. In thus hiding, the crab goes 
nearly, vertically backward into the bottom and then, by 
a few movements, turns slightly, so that the shell rests at 
an angle of about 43 . degrees. The material above settles 
down and effaces all traces of The entrance. It usually 
happens that' the bottom affected by the crab is firm 
enough to render this operation somewhat slow, and it 
rarely -attempts to escape pursuit in such a way. It seems 
probable that concealment is usually adopted as an am- 
bush from which a sudden attack can be made on some 
passing fish. 
In certain places, notably shallow ponds and streams 
which become nearly dry at low tide, the crab may be ob- 
served to dig rather large conical holes, apparently as 
reservoirs) and to take up its position in the deepest part. 
The' work of making - such an excavation often requires 
' two' o.f ., three hours, usu'ally commencing soon after the 
tide has begun to ebb strongly and continuing until the 
edge of the excavation is nearly exposed above the water. 
The animal works from some , suitable point, carrying 
away load after Joad of material clasped between the 
large claw and the lower surface of the front of the shell. 
Itiioosens up the surface with the tips of its second, third 
and fourth pairs of legs, grasps all it can carry and then 
moves off. a few- inches' in the direction of the side which 
bears the load and deoosits it so that it will not roll back. 
Thus the hole is gradually deepend and the surrounding 
circle built up and widened until it has a breadth of abqqt 
a foot, with a depth of perhaps s*ix inches. The crab then 
In practically all the lower anim.als whose bodies are 
Incased in a tough un3-ielding covering, extension in size 
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