Spotted handfish

The spotted handfish (Brachionichthys hirsutus) is a rare Australian fish in the handfish family Brachionichthyidae.[2] It is classified as Critically Endangered on the IUCN Red List 2020 (last assessed 2018). It is a benthic fish usually found at depths of 5 to 10 m, with overall sightings varying from a minimum of 2 to a maximum of 30 m deep.[1][3] The spotted handfish is unusual in that it has highly adapted pectoral fins, which appear like hands (hence the name) and allow it to walk on the sea floor.[4] It has a highly restricted range, being found only in the estuary of Derwent River, Tasmania, and nearby areas.

Spotted handfish
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Lophiiformes
Family: Brachionichthyidae
Genus: Brachionichthys
Species:
B. hirsutus
Binomial name
Brachionichthys hirsutus
(Lacépède, 1804)

Description

The handfishes are a unique, Australian family of anglerfish, the most speciose of the few marine fish families endemic to Australia. The spotted handfish chooses habitats based on the microhabitat features. It tends to prefer complex habitats with features such as depressions and ripple formations filled with shells to avoid predators. Handfish are unusual, small (up to 120 mm or about 4.5 inches in length), slow-moving, benthic fishes that prefer to 'walk' rather than swim. Their pectoral fins are leg-like with extremities resemblant of a sort-of hand (hence their common name). The females are believed to reach sexual maturity after two to three years at lengths of 75–80 mm (about 3 in).

Diet

Currently, little is known regarding their diet, but they have been reported to prey on small shellfish, shrimp, and polychaete worms in the wild. When captive in aquaria, spotted handfish eat mysid shrimp, amphipods, and small live fish. Newly hatched handfish have been observed to do quite well on a diet of small amphipods.

Reproduction

The species spawns sometime during September and October. Females lay a number of eggs varying from 80 to 250 eggs on a variety of vertical objects, including sea grasses, sponges, macrophytic algae, polychaete worm tubes, and stalked ascidians. The eggs are large in diameter measuring approximately 3–4 mm. Handfish have a short pelagic larval period. Therefore, their eggs hatch after 7–8 weeks as fully formed juveniles (6–7 mm SL).[5]

Preservation concerns

The most urgent matter concerning the survival of the species is to address the nuisance threat posed by the presence of an introduced species of starfish (Asterias amurensis), which prey on the fish eggs.[6]

  • The critically endangered spotted handfish
  • Drawing of the spotted handfish
  • Female spotted handfish with her eggs

References
  1. Edgar, G.; Stuart-Smith, R. & Last, P.R. (2020). "Brachionichthys hirsutus". The IUCN Red List of Threatened Species. IUCN. 2020: e.T2958A121210485. doi:10.2305/IUCN.UK.2020-1.RLTS.T2958A121210485.en. Listed as Critically Endangered (CR B1ab v3.1)
  2. "Brachionichthys hirsutus". Integrated Taxonomic Information System. Retrieved 18 April 2006.
  3. Bruce, B. D. & Green, M. A. (March 1998). The Spotted Handfish 1999–2001 Recovery Plan. Spotted Handfish Recovery Team. ISBN 0-643-06165-7.
  4. Fish that Walks – 1999 video
  5. Green, Mark; Bruce, Barry (1998). "Threatened fishes of the world: Brachionichthys hirsutus". Environmental Biology of Fishes. 52 (4): 418. doi:10.1023/A:1007415920088. S2CID 39626211.
  6. Fishbase.org: "Brachionichtys-hirsutus" Check |url= value (help)."Stowaway drives fish to brink of extinction"."Asterias amurensis" (PDF)."Northern Pacific seastar".

Wong, LSC; Lynch, TP; Barnett, NS; Wright, JT; Green, MA; Flynn, DJH. (2018, August 13). Local densities and habitat preference of the critically endangered spotted handfish (Brachionichthys hirsutus): Large scale field trial of GPS parameterised underwater visual census and diver attached camera.


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