PORT PHILLIP BAY


Spiny Seaweed Crab 

Naxia spinosa (Hess, 1865)

View scientific description and taxonomy

Scientific Details

Carapace pear-shaped, strongly narrowing anteriorly, with mesogastric tubercle; surface smooth between groups of strong curled setae. Rostral spines stout, straight, divergent; hepatic spine sharp. Anterolateral angle of basal antennal article with spine. Preorbital spine broad, upturned and antorbital spine sharp; intercalated spine well separated from supraorbital eave, directed obliquely forward. Basal antennal article broad, with distolateral spine only. Walking legs with propodi strongly expanded.

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:
Brachyura
Family:
Majidae
Subfamily:
Majinae
Genus:
Naxia
Species:
spinosa

General Description

Rostral spines stout, straight, divergent; hepatic spine sharp. Anterolateral angle of basal antennal article with spine. Preorbital spine broad, upturned and antorbital spine sharp; intercalated spine well separated from supraorbital eave, directed obliquely forward. Walking legs with propodi strongly expanded. Up to 7 cm long.

Biology

Common in rock pools the Spiny Seaweed Crab hides on rock platforms and in sandy environments rich in algae, sponges or seagrass. These crabs have small hooked hairs on their carapace to which they attach bits of seaweed, sponge or bryozoan. This camouflage, and moving very slowly, makes them hard to see in their natural habitat.

Habitat

Low intertidal to 10 m depth.

Soft substrates

Reefs

Distribution guide

Southern temperate oceans, Kermadec Islands and southern Australia.

Species Group

Crabs and allies Crabs

Depth

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

Water Column

On or near sea floor

Max Size

7 cm

Diet

Organic matter

Harmful

Not harmful but a nip from claws could be painful.

Commercial Species

No

Global Dispersal

Recorded in Australia

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, Spiny Seaweed Crab, Naxia spinosa, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 26 May 2017, http://portphillipmarinelife.net.au:8098/species/5486

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