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Pangurus samuelis - Blueband hermit crab

Geographic range:
Alaska to Baja California

Key features:
Pagurus samuelis is often found in black turban shells Chlorostoma funebralis shells (formerly Tegula). The tips of the walking legs have bright blue bands and the antennae are red with no banding.

Similar species:
Pagurus granosimanus -- Grainyhand hermit crab

bay (rocky shore), exposed rocky shore, kelp forest, protected rocky shore
Pangurus samuelis - Blueband hermit crab image


Primary common name:
Blueband hermit crab
  ITIS code:
Synonymous name(s):
General grouping:
Crabs, barnacles, shrimp, lobster

Geographic Range
Range description:
Alaska to Punta Eugenia (Baja California)
Northern latitude extent:
  Southern latitude extent:
East longitude extent:
  West longitude extent:

Intertidal Height
Lowest intertidal height:
0 meters OR -2 feet
  Highest intertidal height:
0 meters OR 3 feet
Intertidal height notes:
Middle intertidal to lower intertidal, common in tidepools.

Subtidal Depth Range
Minimum depth:
0 meters OR 0 feet
  Maximum depth:
0 meters OR 0 feet
Subtidal depth notes:

bay (rocky shore), exposed rocky shore, kelp forest, protected rocky shore
Habitat notes:
High intertidal to subtidal; rocky intertidal along the outer coast, not often found in inland seas.

Relative abundance:
P. samuelis is abundant along rocky coasts, in mid to lower tidepools, and found occasionally in coarse substrates in bays. One of the most common intertidal hermit crabs on the outer coast, and upper tide pools, especially in southern and central California.

Species Description
General description:
The blueband hermit crab Pagurus samuelis has red antennae and lacks banding. Walking legs have bright blue bands, but smaller crabs have white bands. The body and claw color is brown or green, with a triangular rostrum, chelae with tubercles, and a hard carapace longer than it is wide. The legs and carapace are hairy with setae. The carapace can reach widths of up to 19 mm, and a total length of about 4 cm. Hermit crabs are decapods, with five pairs of legs, including one pair of claws. One claw is much larger than the other, which the hermit crab uses for defense and shredding its food. It uses the smaller claw to eat with. The third and second pairs of legs help the crab to walk, and the other two pairs hold the hermit crab within its shell.
Distinctive features:
P. samuelis is often more willing than other hermit crab species to stick its legs out of its shell to try and escape. This species is especially active in the evening and at night.
Carapace length: up to 19 mm (0.75 in.) Total length: up to 4 cm (1.6 in.)

Natural History
General natural history:
Hermit crabs spend much of their time and energy finding and retaining their snail shell. Competition for shells is related with complex behavioral signaling. Dominance among species and by larger crabs over smaller individuals has been noted frequently. Some species of hermit crabs have strong preferences for certain species of snail shells, such as P. samuelis preferring shells of the black turban snail Chlorosroma funebralis. Further study of the kinds of snail shells that hermit crabs occupy, how they fit, and the relative sizes of the hermits and their shells is needed to increase our understanding of the use of their limited shell resource. Hermit crabs are scavengers and do not kill snails to use the shell. Snail shells can last decades and there is a constant exchange of shells among hermit crabs. As snails die, hermit crabs are attracted to the decaying tissue in the shell, clean it out, and if it is the right size can occupy the shell. Dry shells have a grayish color that blends very well with the dry rocks, providing camouflage to the hermit crab. Among themselves, when not busy reproducing or scavenging, the gregarious hermit crabs fight cautiously but tirelessly, over each other's shells. Most often they are able to retreat into their shells, if both parties have a shell. Adult populations of P. samuelis are rather inactive during the day, but activity levels increase in the late afternoon, and continue through the night until dawn. This activity pattern seems to be a direct response to light levels, not simply an inherent rhythm of behavior. The compound eyes can adapt to day and night conditions by shifts in the position of pigments, as directed by responses to light levels. The relative size of claws is an aid to recognition and hierarchies within social systems. Males with the largest claws are generally dominant. Discontinuity of growth is one of the primary aspects of the lives of arthropods. Ecdysis is the process of shedding the old layer of skin called the exuvia. The additional increase in size only takes a few minutes. However, the total interval between molts represents a dynamic, cyclical process. Following ecdysis the animal is very soft until the cuticle gradually hardens as different areas of the exoskeleton calcify successively. Before its new shell hardens, the crab absorbs water, expanding to a size larger than before the molting process. The abdomen, however, remains soft in hermit crabs, hence the need to cover it with a hard snail shell. The premolt period is signaled by the separation of the epidermis from the cuticle. A mitotic burst precedes the deposition of new cuticular structures, expanding the number of epidermis cells. First the new setae are organized using the previous cuticle as a template. After new setae are organized, pre-exuvial layers are secreted over the general surface of the body. Molting is imminent if the epimeral suture of the crab is visibly split. Exuviae can be distinguished from the empty remains of a dead animal by the absence of pigment from the corneas of the eyestalks of the exuvia. Discovery of a fragile intact exuvia suggests that a soft, recently molted crab may be hiding nearby. The previous owner of the exuvia can by certified by matching details of the pigment patterns of the exuvia, to the soft animal. Comparison of the soft animal and its exuvia demonstrates the growth increment per molt for animals of that size. Decapods are able to cast off (autotomize) their limbs under duress and then regenerate the appendages at subsequent molts. Autotomy is readily demonstrated by squeezing basal segments of an appendage. A specific muscle is stimulated that slices through a cuticular apodeme, severing the limb. This is a highly ordered process. The autotomized limb is always severed at a preformed breakage plane. Upon autotomy, a flap of skin closes over the severed limb base so that scarcely a drop of blood is lost. The regenerating limb forms in a bud that protrudes from the stump of the autotomized limb. Recently regenerated appendages are smaller than normal limbs, but this size discrepancy is no longer apparent after a second or third molt.
Pile perch, sheephead, and spotted kelpfish
Adults scavenge algae, especially Macrocystis pyrifera and dead animal matter.

Feeding behavior
Feeding behavior(s):
Feeding behavior notes:
The diet of P. samuelsis is varied; adults scavenge both plant materials (especially pieces of the large brown algae Macrocystis and Silvetia) and dead animal matter. They have been kept indefinitely in the lab on a diet of Pelvetia canaliculata.
Data supplied by SIMoN Sanctuary Integrated Monitoring Network
Anthopleura xanthogrammica - Giant green anemone

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