radiodonts

19 . 6 . 2026

radiodonta is an extinct order of stem-group anthropods during the cambrian period that lived in water. they were amongst the earliest large predators. some of the most famous species are anomalocaris canadensis, hurdia victoria, peytoia nathorsti, titanokorys gainesi, cambroraster falcatus and amplectobelua symbrachiata.
most radiodonts were significantly larger than the other cambrian fauna, with typical body lengths of large taxa varying from 30 to 50 cm. the largest described radiodont is the aegirocassis benmoulai, which may have grown up to 2 meters long.

radiodonts had lots of different ways to acquire food, which could be categorized as raptorial predators, sediment sifters or suspension, filter feeders. raptorial predators like anomalocaris and amplectobeluids might have been able to catch prey by using their raptorial frontal appendages. sediment sifters like Hurdia and Peytoia form a basket-like trap for raking through sediment and passing food items using their endites.

hermit crabs

11 . 6 . 2026

hermit crabs are anomuran decapod crustaceans of the superfamily paguroidea. they have adapted to occupy empty gastropod shells to protect their abdomens, because their abdominal exoskeletons are soft(non-calcified).
there are over 800 species of hermit crab, most of them elvolved from symmetric, free-swimming larvae to asymmetric, shell-seeking crabs. well, they are not true crabs. they are more closely related to certain kinds of lobsters than crabs. out of the 800+ species, almost all are marine hermit crabs, with a dozen semi-terrestrial species. there is only one species of freshwater hermit crabs.

hermit crabs are omnivorous scavengers and are mostly nocturnal. they eat microscopic mussels and clams, bits of dead animals, and microalgae.

shells

hermit crabs need bigger shells as they grow. since suitable gastropod shells might sometimes be limited resource, there are often competition between the hermits. Shell exchanging is a behavioural interaction observed in all hermit species, in which a hermit crab attempts to exchange its shell with that of another.

Sometimes when a new shell turns up, hermit crabs will form a line from biggest to smallest to see who fits the new shell. The next smallest will take that crab’s hand-me-down home, and so on.

shells used by terrestical hermit crabs have usually been remodelede by previous hermit crab owners. the shells are hollowed out, making them lighter by either physically or chemically carving. these modified shells can last for generations and be used by many hermit crabs.