Platyceratidae is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

s, marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s. This family may belong in the Patellogastropoda or the

Neritimorpha Neritimorpha is a clade of gastropod molluscs that contains around 2,000 extant species of sea snails, limpets, freshwater snails, land snails and slugs. This clade used to be known as the superorder Neritopsina. Etymology The clade’s name, N ...

. Platyceratids are known for the complex

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

relationships they had with crinoids. Platyceratids are thought to have been parasitic on crinoids, either drilling into the stomach to steal the crinoid's food in a form of

kleptoparasitism Kleptoparasitism (originally spelt clepto-parasitism, meaning "parasitism by theft") is a form of feeding in which one animal deliberately takes food from another. The strategy is evolutionarily stable when stealing is less costly than direct f ...

or drilling into the anal sac to feed on the

gonads A gonad, sex gland, or reproductive gland is a mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, ...

or the hindgut. Previous authors have suggested that platyceratids were commensalists which fed on crinoid fecal matter without harming the crinoid, but more recent studies have shown that platyceratids did have a negative effect on their crinoid hosts as would be expected if they were actively parasitic. It has been suggested that the large spines present on many species of crinoids served to deter predators who might damage or harm the crinoid in an effort to feed on the platyceratid snails infesting it. This is the only family in the superfamily Platyceratoidea.

Genera

* '' Platyceras'' Conrad, 1840 -

type genus In biological taxonomy, the type genus (''genus typica'') is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearin ...

* '' Palaeocapulus'' Grabau & Shimer, 1909

References

{{Neritimorpha-stub