#paguridae

[chuck-wills-widow]

Long-claw Hermit Crab (Pagurus longicarpus) June, Southern Maine USA

[flying-potato2]

guy named pvc pipe

[alphynix]

Strange Symmetries #13: The Hermit Crab Cycle

Hermit crabs are crustaceans that first appeared at the start of the Jurassic, about 201 million years ago. Despite their common name they aren't actually true crabs, instead being a classic example of convergently evolving a crab-like body plan via carcinization.

They also have noticeably asymmetric bodies, with abdomens that coil to one side and differently-sized front claws.

Pagurus bernhardus by Arnstein Rønning | CC BY 3.0

And while modern hermit crabs are famous for inhabiting scavenged snail shells, their fossil record suggests this wasn't always the case.

Originally, they seem to have lived in ammonite shells.

Palaeopagurus vandenengeli lived in what is now northern England during the Early Cretaceous, about 130 million years ago. Around 4-5cm long (~1.6-2"), it was found preserved inside the shell of the ammonite species Simbirskites gottschei.

Its left claw was much larger than its right, and together they would have been used to block the shell opening when it was hiding away inside. And while the exact shape of its abdomen isn't known, it probably asymmetrically coiled to the side to accomodate the spiralling shape of the host shell.

Hermit crabs seem to have switched over to using gastropod shells by the Late Cretaceous, around 90-80 million years ago, possibly due to marine snails developing much stronger sturdier shells during this period in response to the increasing prevalence of specialized shell-crushing predators. The more upright snail shells would also have been much easier to drag around the seafloor than ammonite shells – and meant that they were ultimately less affected by the total disappearance of ammonites during end-Cretaceous mass extinction.

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[todropscience]

A tiny and cute hermit crab (Pagurus cf. villosus), living in a dog whelks shell (Nassarius gayi).

[todropscience]

Researchers have just discovered a new hermit crab species!!  Named Candy striped hermit crab (Pylopaguropsis mollymullerae), this species is described based on specimens from the shallow reefs of Bonaire, Lesser Antilles, southern Caribbean Sea. The description it was release in the january issue of zookeys.

Populations of this new species were discovered and photographed in the Bonaire National Marine Park under a large coral ledge, at a depth of 13.7 m, living in crevices close to flaming reef lobsters (Enoplometopus antillensis), and broad banded moray (Channomuraena vittata).

The highly visible color pattern of bright red stripes on white background typical of decapods known to have cleaning symbioses with fish, dense hair-like setaes on antennae, and preference for a crevicular habitat, combined with brief in situ nocturnal observations, suggests the possibility that Candy striped hermit crab engages in “cleaner” activities or functions as a “den commensal” with moray eels.

- In situ video of Pylopaguropsis mollymullerae 

Reference (Open Access): Lemaitre. 2017. Discovery of A New Species of Hermit Crab of the Genus Pylopaguropsis Alcock, 1905 from the Caribbean: “Den Commensal” or “Cleaner”? (Crustacea, Anomura, Paguridae). ZooKeys.

[zoologyverse]

Eupagurus (Hermit crab)

Commonly identified as belonging to the genus Pagurus, Eupagurus is a genus of marine hermit crabs in the Paguridae family. They are distinguished by their asymmetrical, soft, and curled abdomens, which necessitate sheltering in empty snail shells. These decapods are found in marine habitats all over the world, frequently coexisting with sea anemones. Classification of…

Eupagurus (Hermit crab)

[k-star-holic]

Evil community Lee Soo-hyun "Shopping for me, buying 5,000 won accessories"

Source: k-star-holic.blogspot.com

[drhoz]

#1964 - Diacanthurus rubricatus

photo by @purrdence​ 

A large Pagurid hermit crab, endemic to most of the coastlines of New Zealand. I don’t have much other information on them, unfortunately. Often found with anemones living on the shell, and a small copepod Kioloaria tapui that lives in the tip of the shell, discovered in 1982.  ‘tapui’, means ‘close friend'.