| Pagurus longicarpus | |
|---|---|
 | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Crustacea |
| Class: | Malacostraca |
| Order: | Decapoda |
| Family: | Paguridae |
| Genus: | Pagurus |
| Species: | P. longicarpus |
| Binomial name | |
| Pagurus longicarpus | |
Pagurus longicarpus, the long-wristed hermit crab, is a common hermit crab found along the Atlantic and Gulf coasts of the United States and the Atlantic coast of Canada. [2]
This species of hermit crab can reach a shell length of up to half an inch in size. P. longicarpus coloration can vary, but body color is most commonly gray, green or white. The right claw of P. longicarpus is much larger than the left, and each claw has a tan or gray stripe down the middle. [3]
The long-wristed hermit crab inhabits the empty shells of gastropods such as periwinkles, snails, and slugs for mobile shelter and protection of their soft abdomens. They anchor themselves into the shells by wrapping their abdomens around the columella, or axis, inside the vacant shell. [4] Hermit crabs cannot produce their own shells, and therefore must scavenge for abandoned ones. [5] [6] [7] Shell selection plays many crucial roles in P. longicarpus, such as providing protection from predators, desiccation and salinity stress, as well as influencing competition, population size, and reproductive behaviors in the species. [6]
P. longicarpus is commonly found along the Atlantic coast of Canada and the United States, from Nova Scotia to Northeastern Florida, as well as along the Gulf coast of the United States to Texas. [2] These hermit crabs can be found in intertidal and subtidal Atlantic environments on a variety of substrates and at depths of up to 200 meters. [8] Most commonly, P. longicarpus is found in shallow tidal pools during the months of April to October, and in deeper and warmer waters during the fall and winter months. P. longicarpus faces extreme temperature and salinity fluctuations while inhabiting tidal pools due to the rising and falling tides, as well as changing climate. [6] On hot, sunny days, there is often a rapid increase in tidal pool temperature and salinity, whereas on cooler, rainier days, salinity and temperature can rapidly decrease. Rising tides can also alter tidal pool conditions to those of the surrounding ocean. [6] Due to these harsh living conditions, P. longicarpus depends heavily on its shell to cope with changing conditions. These fluctuating conditions can also impact shell selection in the species and determine species distribution within intertidal and subtidal regions. [2] [6]
Long-wristed hermit crabs are scavenger feeders with a broad diet consisting of detritus, organic material found in ocean surface foam, microcrustaceans and algae. [8] [9] Feeding is performed by scooping sand or other substrate with the chelipeds, ripping and tearing food, and then passing it to the mouth for consumption. [10]
The major predators of P. longicarpus include birds, fish, snails, octopuses and other crabs, including the green crab. [3] [7] Hermit crab shells are crucial for protection and minimizing predation, and therefore proper shell selection is vital. P. longicarpus will avoid selecting shells with extensive damage because they are more vulnerable to predation. The most common type of damage to hermit crab shells is the presence of small holes. These holes are caused by the drilling of nacticid gastropods in order to prey on the original gastropod hosts of the shell. [7]
Intraspecific competition within this species is very common and is most often triggered by lack of resources. [11] One of the most important limited resources to hermit crabs is their shell, which is key to their survival and reproductive success. Finding an appropriately sized shell is valuable for P. longicarpus. From an energetic standpoint, if a shell is too large, crabs will extend unnecessary energy carrying and maneuvering it. Alternatively, if the shell is too small, they could suffer from increased predation and desiccation. [6] Shell selection also plays a role in reproductive success in P. longicarpus. Reproductive success is positively correlated with a larger shell size, and the rate of growth of the crabs can be stimulated by inhabiting larger shells. [5] P. longicarpus also will not feed unless housed in the proper sized shell, ultimately leading to starvation and death. [4] Each of the consequences of incorrect shell size places a strong selective pressure on obtaining the perfect shell, which often results in aggressive and competitive interactions within the species. [11] In addition to fighting over mates and food, P. longicarpus will fight over shells. Larger crabs or crabs with less suitable shells will often forcibly remove other crabs with more desirable shells by clasping the chelae, or legs, of the occupant with its pincers, which allows them to takeover the desired shell. [4] [11] Along with predation, shell availability is a major factor in determining P. longicarpus population size. [7]
P. longicarpus breeding season occurs from late March until October with the peak breeding in April. The main period of reproduction in the species occurs during the spring. [8] Male hermit crabs will compete with other males for available females during breeding season. P. longicarpus, like many crustaceans, performs precopulatory mate-guarding behaviors, where males will grasp ahold of the female’s shell once the female releases a pheromone signaling sexual maturity. [12] Male and female crabs can be differentiated based on their pleopod morphology. Males have two pleopods, while females have three branching pleopods where her eggs are attached. [13] P. longicarpus have sexual internal fertilization and must exit their shells in order to mate. After fertilization, the female houses the eggs inside her shell where they grow and develop. Larvae are later released into the surrounding ocean where they undergo several planktonic growth stages before developing into adult hermit crabs. [3]
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen), usually hidden entirely under the thorax. They live in all the world's oceans, in fresh water, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. Many other animals with similar names – such as hermit crabs, king crabs, porcelain crabs, horseshoe crabs, and crab lice – are not true crabs, but many have evolved features similar to true crabs in a process of carcinisation.
Hermit crabs are anomuran decapod crustaceans of the superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit crab, most of which possess an asymmetric abdomen concealed by a snug-fitting shell. Hermit crabs' non-calcified abdominal exoskeleton makes their exogenous shelter system obligatory. Hermit crabs must occupy shelter produced by other organisms, or risk being defenseless.
Pagurus pollicaris is a hermit crab commonly found along the Atlantic coast of North America from New Brunswick to the Gulf of Mexico. It is known by a number of common names, including gray hermit crab, flat-clawed hermit crab, flatclaw hermit crab, shield hermit crab, thumb-clawed hermit crab, broad-clawed hermit crab, and warty hermit crab.
The decapod crustacean, such as a crab, lobster, shrimp or prawn, is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in various groups these may be reduced or missing. They are, from head to tail:
Pagurus bernhardus is the common marine hermit crab of Europe's Atlantic coasts. It is sometimes referred to as the common hermit crab or soldier crab. Its carapace reaches 3.5 centimetres (1.4 in) long, and is found in both rocky and sandy areas, from the Arctic waters of Iceland, Svalbard and Russia as far south as southern Portugal, but its range does not extend as far as the Mediterranean Sea. It can be found in pools on the upper shore and at the mean tide level down to a depth of approximately 140 metres (460 ft), with smaller specimens generally found in rock pools around the middle shore and lower shore regions, with larger individuals at depth. P. bernhardus is an omnivorous detritivore that opportunistically scavenges for carrion, and which can also filter feed when necessary.
Coenobita brevimanus is a species of terrestrial hermit crab belonging to the family Coenobitidae, which is composed of coastal living terrestrial hermit crabs. From there it belongs to the genus Coenobita, one of two genera split from the family, which contains sixteen species. The Latin origins of the species name, brevimanus, come from the adjective brevis ("small") and the noun manus ("hands"). It is known as the Indos crab or Indonesian crab because it is primarily distributed throughout the Indo-Pacific.
Pagurus novizealandiae, or the New Zealand hermit crab is a hermit crab of the family Paguridae, endemic to New Zealand. Its body is up to 16 millimetres (0.63 in) wide.
Calcinus elegans, also known as the blue line hermit crab, is a small, tropical hermit crab.
Pagurus armatus, the armed hermit crab or black-eyed hermit crab, is a species of hermit crab found in the eastern Pacific Ocean of the United States and British Columbia, Canada.
The coconut crab is a species of terrestrial hermit crab, also known as the robber crab or palm thief. It is the largest terrestrial arthropod in the world, with a weight up to 4.1 kg (9.0 lb). It can grow to up to 1 m in length from each tip to tip of the leg. It is found on islands across the Indian Ocean, and parts of the Pacific Ocean as far east as the Gambier Islands and Pitcairn Islands, similar to the distribution of the coconut palm; it has been extirpated from most areas with a significant human population, including mainland Australia and Madagascar. Coconut Crabs also live off the coast of Africa near Zanzibar.
Diogenes pugilator is a species of hermit crab, sometimes called the small hermit crab or south-claw hermit crab. It is found from the coast of Angola to as far north as the North Sea, and eastwards through the Mediterranean Sea, Black Sea and Red Sea. Populations of D. pugilator may be kept in check by the predatory crab Liocarcinus depurator.
Dardanus pedunculatus, the anemone hermit crab, is a species of hermit crab from the Indo-Pacific region. It lives at depths of up to 27 m and collects sea anemones to place on its shell for defence.
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The larvae of crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults, more-so than where the larvae are planktonic, and thereby easily caught.
Pagurus sinuatus is a large species of hermit crab found in Australia and the Kermadec Islands. It is red or orange in colour with coloured bands on the legs and patches on the body.
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.
Calcinus tubularis is a species of hermit crab. It is found in the Mediterranean Sea and around islands in the Atlantic Ocean, where it lives below the intertidal zone. Its carapace, eyestalks and claws are marked with numerous red spots. C. tubularis and its sister species, C. verrilli, are the only hermit crabs known to show sexual dimorphism in shell choice, with males using normal marine gastropod shells, while females use shells of gastropods in the family Vermetidae, which are attached to rocks or other hard substrates.
Porcellanopagurus edwardsi is a species of hermit crab that lives in the waters around New Zealand and its subantarctic islands.
Pagurus forbesii is a species of hermit crab in the family Paguridae. It is found in the northeastern Atlantic Ocean and the Mediterranean Sea.
Pagurus acadianus, the Acadian hermit crab, is a species of hermit crab in the family Paguridae. It is found in Western Atlantic Ocean.
Pagurus dalli, commonly known as the whiteknee hermit, is a species of hermit crab in the family Paguridae. It is found in the northeastern Pacific Ocean at depths down to about 276 m (900 ft). It usually lives in a mutualistic symbiosis with a sponge, or sometimes a hydroid.