A preserved squid specimen collected from a sperm whale stomach during the 1955–56 whaling season has been identified as Mobydickia poseidonii, representing an entirely new family of oceanic squid named Mobydickidae, according to a study published in the July 2025 issue of the Zoological Journal of the Linnean Society.
Anatomy Reveals a New Family, Genus, and Species
Researchers Sam Arnold, David Nos, Raquel Sáez-Liante, and Fernando Ángel Fernández-Álvarez discovered the unique specimen while revising the diversity of the sharp-ear enope squid, Ancistrocheirus lesueurii. According to the study, the animal possessed a dorsal mantle length of 175 millimetres, a soft, gelatinous, pale body, and a short tail. It lacked the light-producing organs, or photophores, expected in its previously assigned family. Its fins extended for less than half the mantle length, while its beak, internal shell, and arm hooks displayed a unique combination of features. The hooks feature a large central cusp accompanied by smaller accessory claws, creating a trident-like shape that inspired the species name poseidonii, after the Greek sea god Poseidon, according to the authors.
From Whaling Record to Museum Specimen
The specimen was originally collected by Malcolm Clarke from the stomach contents of a male sperm whale during the 1955–56 whaling season, with surviving records placing the whale in a broad Antarctic or sub-Antarctic zone that includes the Bellingshausen Sea, Drake Passage, and Scotia Sea. Following Clarke’s death in 2013, his research collection moved to London’s Natural History Museum before being loaned to the Marine Biological Reference Collections at the Institut de Ciències del Mar (ICM-CSIC) in Barcelona. Because oceanic squid are difficult to collect intact due to net damage and deep-water habits, whale stomachs remain a vital, if irregular, sampling route for studying elusive marine life.
Did You Know?
The genus name Mobydickia honors Herman Melville’s famous sperm whale, Moby-Dick, while also highlighting the specimen’s unusually white, low-pigmentation preserved body.
Hidden Diversity in Oceanic Squid
The identification of Mobydickia emerged from a wider morphological and molecular investigation of 46 individuals within the genus Ancistrocheirus. While DNA barcoding helped researchers separate several cryptic lineages within Ancistrocheirus, the old Antarctic specimen could not supply molecular evidence. Instead, its classification into the new family Mobydickidae relied entirely on anatomical differences, including mantle and fin proportions, beak shapes, and hook structures. The World Register of Marine Species subsequently included Poseidon’s squid in its Top Ten Remarkable Marine Species of 2025, and the paper calls it the first new family of oceanic squid erected since the bigfin squid family, Magnapinnidae, was described in 1998.
Frequently Asked Questions
Where was the Mobydickia poseidonii specimen found?
The specimen was recovered from the stomach of a male sperm whale captured during the 1955–56 whaling season in a broad Antarctic or sub-Antarctic region encompassing the Bellingshausen Sea, Drake Passage, and Scotia Sea, according to historical records.
Why is this discovery considered significant by taxonomists?
According to the research published in the Zoological Journal of the Linnean Society, it establishes the first new family of oceanic squid (Mobydickidae) since 1998, based on distinctive anatomical features that separate it from all other known squid families.
Is Mobydickia poseidonii currently observed living in the wild?
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