Pagurus samuelis
Encyclopedia
Pagurus samuelis, the blueband hermit crab, is a species
of hermit crab
from the west coast of North America, and the most common hermit crab in California. It is a small species, with distinctive blue bands on its legs. It prefers to live in the shell of the black turban snail
, and is a nocturnal scavenger
of algae and carrion.
width of up to 19 mm (0.748031496062992 in). The base colour of the exoskeleton
is brown or green, but the antennae
are red, and adults have bright blue bands near the tips of their legs. In smaller individuals, the bands may be white. The legs and carapace are covered in setae, and the rostrum
at the front of the carapace is triangular.
to Punta Eugenia in Baja California
, Mexico
. It was formerly thought to also occur in Japan
, but the Japanese specimens which were formerly assigned to this species are now recognised as Pagurus filholi. P. samuelis is the commonest hermit crab in the higher tide pool
s in California
, being ten times more abundant than P. granosimanus.
Pagurus samuelis prefers to use the discarded shell
of the black turban snail
, Tegula funebralis. They are chiefly nocturnal scavenger
s that feed on algae
, especially the giant kelp Macrocystis pyrifera
, and carrion
. In a laboratory setting, P. samuelis can survive on a diet of Pelvetia canaliculata
. Predators of P. samuelis include fishes such as the pile perch (Rhacochilus vacca), California sheephead
(Semicossyphus pulcher) and the spotted kelpfish, Gibbonsia elegans
.
In the breeding season
, males carry females on their backs, sometimes for more than a day. Eggs
are produced from May to July, and are carried on the female's abdomen, inside the shell.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of hermit crab
Hermit crab
Hermit crabs are decapod crustaceans of the superfamily Paguroidea. Most of the 1100 species possess an asymmetrical abdomen which is concealed in an empty gastropod shell that is carried around by the hermit crab.-Description:...
from the west coast of North America, and the most common hermit crab in California. It is a small species, with distinctive blue bands on its legs. It prefers to live in the shell of the black turban snail
Black Turban Snail
The black turban snail, scientific name Tegula funebralis, is a species of medium-sized sea snail with gills and an operculum, a marine gastropod mollusc in the family Turbinidae.This is an Eastern Pacific Ocean species.-Distribution:...
, and is a nocturnal scavenger
Scavenger
Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
of algae and carrion.
Description
Pagurus samuelis is a small hermit crab, at up to a total length of 40 mm (1.6 in) and a carapaceCarapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
width of up to 19 mm (0.748031496062992 in). The base colour of the exoskeleton
Exoskeleton
An exoskeleton is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton of, for example, a human. In popular usage, some of the larger kinds of exoskeletons are known as "shells". Examples of exoskeleton animals include insects such as grasshoppers...
is brown or green, but the antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
are red, and adults have bright blue bands near the tips of their legs. In smaller individuals, the bands may be white. The legs and carapace are covered in setae, and the rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....
at the front of the carapace is triangular.
Distribution
Pagurus samuelis is found from AlaskaAlaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
to Punta Eugenia in Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
, Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. It was formerly thought to also occur in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, but the Japanese specimens which were formerly assigned to this species are now recognised as Pagurus filholi. P. samuelis is the commonest hermit crab in the higher tide pool
Tide pool
Tide pools are rocky pools by oceans that are filled with seawater. Many of these pools exist as separate entities only at low tide.Tide pools are habitats of uniquely adaptable animals that have engaged the special attention of naturalists and marine biologists, as well as philosophical...
s in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, being ten times more abundant than P. granosimanus.
Ecology and life cycle
Gastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...
of the black turban snail
Black Turban Snail
The black turban snail, scientific name Tegula funebralis, is a species of medium-sized sea snail with gills and an operculum, a marine gastropod mollusc in the family Turbinidae.This is an Eastern Pacific Ocean species.-Distribution:...
, Tegula funebralis. They are chiefly nocturnal scavenger
Scavenger
Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
s that feed on algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, especially the giant kelp Macrocystis pyrifera
Macrocystis pyrifera
Macrocystis pyrifera, commonly known as Giant kelp or Giant bladder kelp, is a species of kelp , and one of four species in the genus Macrocystis...
, and carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
. In a laboratory setting, P. samuelis can survive on a diet of Pelvetia canaliculata
Pelvetia canaliculata
Pelvetia canaliculata, channelled wrack, is a very common brown alga found on the rocks of the upper shores of Europe.-Description:...
. Predators of P. samuelis include fishes such as the pile perch (Rhacochilus vacca), California sheephead
California sheephead
The California sheephead is a wrasse native to the eastern Pacific Ocean. Its range is from Monterey Bay, California to the Gulf of California, Mexico.- Description :...
(Semicossyphus pulcher) and the spotted kelpfish, Gibbonsia elegans
Gibbonsia elegans
Gibbonsia elegans, known commonly as the Spotted kelpfish in United Kingdom and the United States, is a species of clinid in the genus Gibbonsia. It is a subtropical blenny found in the eastern Pacific Ocean. It was named by J.G. Cooper in 1864, and can reach a maximum length of 16 centimetres...
.
In the breeding season
Breeding season
The breeding season is the most suitable season, usually with favourable conditions and abundant food and water, for breeding among some wild animals and birds . Species with a breeding season have naturally evolved to have sexual intercourse during a certain time of year in order to achieve the...
, males carry females on their backs, sometimes for more than a day. Eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
are produced from May to July, and are carried on the female's abdomen, inside the shell.