PORT PHILLIP BAY


Hairy Porcelain Crab 

Polyonyx transversus (Haswell, 1882)

View scientific description and taxonomy

Scientific Details

Carapace about 1.4 times as broad as long, with fringe of hairs along frontal margin; lateral margins unarmed. Antenna peduncle with moveable articles excluded from orbit by projection of basal article meeting anterior margin of carapace. Chelipeds large, unequal, merus with vestigial lobe; carpus hairy on inner margin, developed into a prominent, convex lobe, broadest distally and unarmed; chela dorsally hairy. Propodus of walking legs with more than 12 spinules on lower margin; dactylus with lower claw larger than upper, with 2 stout spines on lower margin. Telson with 7 plates. Pleopods usually present in males.

Source: Poore, G.C.B. (2004) Marine decapod Crustacea of southern Australia. A guide to identification (with chapter on Stomatopoda by Shane Ahyong). CSIRO Publishing, Melbourne, 574 pp.

Taxonomy

Phylum:
Arthropoda
Subphylum:
Crustacea
Class:
Malacostraca
Subclass:
Eumalacostraca
Superorder:
Eucarida
Order:
Decapoda
Suborder:
Pleocyemata
Infraorder:
Anomura
Family:
Porcellanidae
Genus:
Polyonyx
Species:
transversus

Other Names

  • Commensal Porcelain Crab

General Description

Carapace much broader than long, with fringe of hairs along frontal margin. Fourth segment (merus) of claws (cheliped) with vestigial lobe; fifth segment (carpus) hairy on inner margin, developed into a prominent, convex lobe, broadest distally and unarmed; claws dorsally hairy. Sixth segment (propodus) of walking legs with more than 12 spinules on lower margin; seventh segment (dactylus) with lower claw larger than upper, with 2 stout spines on lower margin. They are often taken in the paper tubes of the large polychaete Chaetopterus variopedatus and may be living commensally with this species. Up to 11 mm wide.

Biology

This unusual porcelain crab is likely to be seen only in samples of mud dug from the bottom of Port Phillip Bay or similar environments. It lives in a papery tube shared with a large polychaete worm, sometimes in male-female pairs. The dirty, muddy-orange carapace is wider than long and the claws are hairy. Another similar six-legged true crab, Hexapinus granuliferus, has the same preferences.

Habitat

Intertidal, to depths of 24 m.

Soft substrates

Distribution guide

Southern temperate oceans, including southern Australia.

Species Group

Crabs and allies False crabs

Depth

Shore (0-1 m)
Shallow (1-30 m)

Water Column

On or near sea floor

Max Size

11 mm

Diet

Organic matter

Harmful

Not harmful but a nip from large claws could be painful

Commercial Species

No

Global Dispersal

Native to Australia

Species Code

MoV 740

Conservation Status

  • DSE Advisory List : Not listed
  • EPBC Act 1999 : Not listed
  • IUCN Red List : Not listed

Author

article author Taylor, J.

Dr. Jo Taylor is the Sciences Collections Online Coordinator at Museum Victoria.

Author

article author Poore, G.C.B.

Dr. Gary Poore is Principal Curator Emeritus at Museum Victoria.

citation

Cite this page as:
Taylor, J. & Poore, G.C.B., 2011, Hairy Porcelain Crab, Polyonyx transversus, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 23 Aug 2017, http://portphillipmarinelife.net.au:8098/species/5498

Text: creative commons cc by licence