Idiosepiidae, also known as the pygmy squids, is a

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 ...

squids A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also called ''squi ...

in the

superorder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

Decapodiformes Decapodiformes is a superorder of Cephalopoda comprising all cephalopod species with ten limbs, specifically eight short arms and two long tentacles. It is hypothesized that the ancestral coleoid had five identical pairs of limbs, and that one ...

. They are the smallest known squids. It is the only family in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

order Idiosepida and the monotypic superfamily Idiosepioidea. Phylogenomic analyses have shown that species in the family Idiosepiidae are sister to all other

Description

Idiosepiidae are the smallest known squids: males can grow to about and females to about in mantle length. The mantle is elongate, obovate to cigar-shaped, with its posterior margin bluntly pointed at the distal tip. Their internal chitinous shell is vestigial, and the dorsal surface of the mantle has a unique oval adhesive organ, which secretes a sticky substance and is used to attach itself to seaweed or seagrass blades. The head is prominent while the arms are short. In males, both ventral arms are differentiated, but they are also different from each other. Females are generally larger and achieve sexual maturity later than males.

Distribution and ecology

Idiosepiidae have an Indo-west Pacific distribution, from South Africa in the west to Japan and Russia in the east. They appear to be short-lived and have multiple generations per year. In temperate climates their population declines at the end of the warm season. They generally live in shallow water among seagrass and mangroves. They often adhere themselves to substrate, enabling camouflage and concealment during the day. They are solitary. Mating is promiscuous with multiple matings. Young individuals are planktonic. They appear to be

sit-and-wait predator Ambush predators or sit-and-wait predators are carnivorous animals that capture their prey via stealth, luring or by (typically instinctive) strategies utilizing an element of surprise. Unlike pursuit predators, who chase to capture prey using ...

s. They feed mainly on small crustaceans like Latreutes acicularis.

Genera

The following genera are recognised in the family Idiosepiidae: *''

Idiosepius ''Idiosepius'' is a genus of squids in the family Idiosepiidae. Most well known for their incredibly tiny size, these squids range from 10 to 18 mm (0.39 to 0.75 in) in adult specimens. Members of this genus are of no interest to commercial fish ...

'' Steenstrup, 1881 *'' Kodama'' Reid, Sato, Jolly & Strugnell, 2023Amanda Reid, Noriyosi Sato, Jeffrey Jolly & Jan Strugnell. 2023. Two New Pygmy Squids, Idiosepius kijimuna n. sp. and Kodama jujutsu n. gen., n. sp. (Cephalopoda: Idiosepiidae) from the Ryukyu Islands, Japan. Marine Biology. 170: 167. DOI: 10.1007/s00227-023-04305-1 *'' Xipholeptos'' Reid & Strugnell, 2018

References

{{Taxonbar, from=Q2196443 Decapodiformes Cephalopod families Taxa named by Adolf Appellöf