University Of Tasmania

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Native spider crab causes high incidence of sub-lethal injury to the introduced seastar Asterias amurensis

conference contribution
posted on 2023-05-23, 06:58 authored by Scott LingScott Ling, Craig JohnsonCraig Johnson
The northern Pacific seastar, Asterias amurensis (Lütken), is an invasive species established throughout the Derwent Estuary, southeast Tasmania. Here we report on field observations of predation on the seastar within its new environment. The spider crab Leptomithrax gaimardii (family Majidae), which characteristically aggregates in shallow water in winter, used its chelae to tear the body wall of A. amurensis and completely consume the seastar. Typically, the predatory interaction resulted in sub-lethal injury (arm damage) to the seastar. Sampling in the area of an aggregation of spider crabs revealed that ~70% (ranging from 50-87%) of the A. amurensis population incurred sub-lethal arm damage consistent with spider crab attack. Spider crabs were observed at other sites in the estuary, but were transient and rates of arm injury at these sites were much lower, ranging from 7-33%. The most common form of injury sustained by A. amurensis in the presence of spider crabs was damage to arm tips (62% of all injuries), followed by full arm loss (34%) and half-arm loss (5%). Near the peak of the ~2 month spider crab aggregation, very few injured seastars displayed evidence of arm regeneration, however rates of arm regeneration increased rapidly as the localised spider crab aggregation dispersed. Smaller A. amurensis were disproportionately represented among the injured seastars, while observations in situ and in aquaria revealed that injury may frequently occur during competition for mussel prey. These observations suggest that native predators within the seastars new range may be capable of inflicting localised seasonal impacts on this important introduced pest.


Publication title

Proceedings of the 13th International Echinoderm Conference


CR Johnson




Institute for Marine and Antarctic Studies


CRC Press

Place of publication


Event title

13th International Echinoderm Conference

Event Venue

Hobart, Tasmania, Australia

Date of Event (Start Date)


Date of Event (End Date)


Rights statement

Copyright 2013 Taylor & Francis Group

Repository Status

  • Restricted

Socio-economic Objectives

Effects of climate change on Australia (excl. social impacts)