Spotted handfish (Brachionichthys hirsutus)

Description

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Spotted handfish fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Spotted handfish description

The spotted handfish (Brachionichthys hirsutus) is one of the world's most endangered marine fish. This extremely distinctive fish is almost pear-shaped ⁽²⁾ and unusually, has hand-like 'paired fins' that enable it to 'walk' along the seafloor ⁽³⁾; both the pectoral and ventral fins are used in this locomotion ⁽⁴⁾. When swimming through the water, the unpaired or 'median' fins (such as the tail and anal fin) are used ⁽⁴⁾. These fish are cream in colour with a myriad of dusky brown, and occasionally yellow-brown spots ⁽⁴⁾, the pattern of which is unique to each individual ⁽³⁾. Some individuals also have orange markings on their fins. Handfish have a small lure just above their mouth, the function of which is unknown but does not appear to be used to entice prey ⁽⁴⁾.

Size

Length: 10 - 15 cm ⁽²⁾

Spotted handfish biology

Spotted handfish spawn during September and October ⁽³⁾, the male enticing the female by his courtship display ⁽⁵⁾. Compared to many other fish, the female produces a relatively small number of eggs; around 80 to 250 eggs are spawned and these are often positioned around the base of a sea squirt (a jelly-like invertebrate) ⁽³⁾. The female guards the eggs for seven to eight weeks until the fully-formed juveniles hatch. These tiny young measure a mere six to seven millimetres and when they emerge, move straight to the bottom of the seabed, instead of dispersing ⁽³⁾.

Spotted handfish feed by sucking in prey items ⁽⁵⁾, including shrimps, small fish and small crustaceans such as amphipods ⁽³⁾.

Spotted handfish range

Endemic to the lower Derwent River estuary in Tasmania, the spotted handfish was a relatively common species until the 1980s. The species has declined massively, however; only three breeding colonies were known to exist in 1998 ⁽³⁾.

Spotted handfish habitat

The bottom-dwelling spotted handfish is found on coarse to fine sand and silt, in coastal waters from depths of 2 to 30 metres ⁽³⁾.

Spotted handfish status

The spotted handfish is classified as Critically Endangered (CR) on the IUCN Red List ⁽¹⁾.

Spotted handfish threats

The spotted handfish was common in the lower Derwent River estuary until the mid 1980s, when the species underwent a catastrophic decline ⁽²⁾. Although unproven, it is thought that the introduction of the northern Pacific seastar (Asterias amurensis) to Tasmania at this time may be the key to the decimation of the handfish population ⁽³⁾. These seastars are voracious predators of shellfish and it is thought that they may also eat the eggs of handfish or the sea squirts upon which the eggs are attached ⁽²⁾. The deterioration of coastal habitats due to development may also be involved in the decline ⁽³⁾. This species is under added threat from its vastly reduced population, limited dispersal, restricted distribution and low reproductive rate ⁽³⁾.

Spotted handfish conservation

Just two spotted handfish were reported between 1990 and 1994; this dire state of the population led to the formation of the Spotted Handfish Recovery Team in 1996 ⁽³⁾. The Recovery Team consists of a number of government agencies concerned with saving this rare, and bizarre, fish. Research into existing wild populations and the development of captive breeding techniques are some of the priorities of the recovery plan ⁽³⁾. Initial work has been encouraging, with successful breeding attempts from two adult pairs of spotted handfish at the Tasmanian Department of Primary Industry and Fisheries Aquaculture ⁽²⁾. A captive population may be used in a future re-introduction programme to restore these fish to some of their previous range ⁽⁶⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

For more information on the spotted handfish see:

•  Bruce, B.D. and Green, M.A. (1998) The Spotted Handfish 1999-2001 Recovery Plan. Department of the Environment, Water, Heritage, and the Arts, Canberra, Australia. Available at:
  www.environment.gov.au/biodiversity/threatened/publications/recovery/spotted-handfish/

For more information on handfish species, see:

http://news.nationalgeographic.com/news/2010/05/photogalleries/100524-new-species-handfish-walk-science-pictures/

• National Geographic Online

Authentication

Authenticated (18/11/02) by Rudie Kuiter. Managing Editor, Zoonetics erBOOKS.

Glossary

Amphipods

A group of small shrimp-like crustaceans that includes sandhoppers, beach hoppers, and water lice.

Anal fin

In fish, an unpaired fin on the under surface of a fish, behind the anus.

Colonies

A group of organisms living together. Individuals in the group are not physiologically connected and may not be related, such as a colony of birds. Another meaning refers to organisms, such as bryozoans, which are composed of numerous genetically identical modules (also referred to as zooids or ‘individuals’), which are produced by budding and remain physiologically connected.

Crustaceans

Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Invertebrate

Animals with no backbone.

Pectoral fins

In fish, the pair of fins that are found one on each side of the body just behind the gills. They are generally used for balancing and braking.

Re-introduction

An attempt to establish a native species back into an area where it previously occurred.

Ventral fins

In fish, the pair of fins found on the underside of the body

References

1. IUCN Red List (April, 2008)
   http://www.iucnredlist.org
2. Oz Reef Marine Park (August, 2002)
   http://ozreef.org/reference/handfish.html
3. Bruce, B.D. and Green, M.A. (1998) The Spotted Handfish 1999-2001 Recovery Plan. Department of the Environment, Water, Heritage, and the Arts, Canberra, Australia. Available at:
   http://www.dpiw.tas.gov.au/inter.nsf/Attachments/LJEM-6WG6FA/$FILE/Spotted%20Handfish%20recovery%20plan%201999-2000.pdf
4. Kuiter, R. (2002) Pers. comm.
5. The Savage South(Sunburnt Pictures tx. 1998).
6. Bruce, B.D. and Green, M.A. (1998) The Spotted Handfish 1999-2001 Recovery Plan. Department of the Environment, Water, Heritage, and the Arts, Canberra, Australia.