Idiosepiidae
{{Short description|Family of molluscs}}
{{Automatic taxobox
| image = Tropical Pygmy Squid (Idiosepius pygmaeus) (25377304317).jpg
| image_caption = Idiosepius pygmaeus
| display_parents = 3
| taxon = Idiosepiidae
| parent_authority = Appellöf, 1898
}}
Idiosepiidae, also known as the pygmy squids, is a family of squids in the superorder Decapodiformes. They are the smallest known squids.
It is the only family in the monotypic order Idiosepida{{WoRMS |title=Idiosepida |id=1454586 |db=Mollusca |access-date=23 April 2023 }} and the monotypic superfamily Idiosepioidea.{{WoRMS |title=Idiosepioidea Appellöf, 1898 |id=1454587 |db=Mollusca |access-date=23 April 2023 }} Phylogenomic analyses have shown that species in the family Idiosepiidae are sister to all other Decapodiformes.{{Cite journal |last1=Anderson |first1=Frank E. |last2=Lindgren |first2=Annie R. |date=2021-03-01 |title=Phylogenomic analyses recover a clade of large-bodied decapodiform cephalopods |url=https://www.sciencedirect.com/science/article/pii/S1055790320303109 |journal=Molecular Phylogenetics and Evolution |volume=156 |pages=107038 |doi=10.1016/j.ympev.2020.107038 |issn=1055-7903|doi-access=free }}
Description
Idiosepiidae are the smallest known squids: males can grow to about {{convert|15|mm|in|1|abbr=on}} and females to about {{convert|21|mm|in|1|abbr=on}} 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.[https://books.google.com/books?id=5e4aah3VXZQC&dq=Idiosepius+vestigial+shell+adhesive+organ&pg=PA200 Mollusca: Aplacophora, Polyplacophora, Scaphopoda, Cephalopoda, Volum 17] 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.{{Cite journal |last1=Kasugai |first1=Takashi |last2=Segawa |first2=Susumu |date=2005 |title=LIFE CYCLE OF THE JAPANESE PYGMY SQUID IDIOSEPIUS PARADOXUS (CEPHALOPODA: IDIOSEPIIDAE) IN THE ZOSTERA BEDS OF THE TEMPERATE COAST OF CENTRAL HONSHU, JAPAN |url=https://www.researchgate.net/publication/242419964 |journal=Phuket Mar. Biol. Cent. Res. Bull. |issue=66 |pages=249–258}}
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 predators. They feed mainly on small crustaceans like Latreutes acicularis.
Genera
The following genera are recognised in the family Idiosepiidae:
- Idiosepius 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
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{{WoRMS |title=Idiosepiidae Appellöf, 1898 |id=153037 |db=Mollusca |access-date=23 April 2023 }}
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