Diet, feeding behavior, and surface morphology of the multi-armed Antarctic sea star Labidiaster annulatus (Echinodermata Asteroidea)

Abstract

Labidiaster annulatus is a large, multi-armed sea star common in moderate depths along the Antarctic Peninsula and off the islands of the Scotia Arc. Analyses by frequency of occurrence and several volumetric methods of stomach contents from 194 individuals from South Georgia, the South Sandwich Islands, and the Antarctic Peninsula show L. annulatus is an active and opportunistic predator and scavenger on prey from at least 10 phyla. Most common prey are euphausiids and amphipods which are caught initially by large, crossed, toothed pedicellariae arranged in wreaths on annuli along the arms and subsequently retained and passed to the oral surface and along the ambulacral groove to the mouth by the action of flexible arms and tube feet. L. annulatus obtains food, including activelyswimming crustaceans and small fish, directly from the water column, and to a lesser degree from within and on the substrate. Patterns of surface ciliation suggest that no methods of feeding involving cilia are utilized. Differences in the size and function of crossed pedicellariae, sources and types of prey and methods of prey capture now suggest that L. annulatus is not an ecological equivalent of Pycnopodia helianthoides from western North America.

Trophic biology of antarctic shallow-water echinoderms

“…One of the most active predatory asteroids is Labidiaster annulatus, which Dearborn (1977) likens to the voracious Pacific coast asteroid Pycnopodia helianthoides. However, Dearborn et al (1991) note that these 2 sea stars differ in that L. annulatus obtains a high percentage of its prey from the water column, while P. helianthoides primarily feeds on bivalves and echinoids. L, annulatus feeds on 50 or more prey types (Dearborn & Edwards 1984, Dearborn et al 1991, including fish, euphausids, ophiuroids, gastropods, bivalves, crinoids, polychaetes, asteroids, isopods, amphipods and echinoids.…”

“…However, Dearborn et al (1991) note that these 2 sea stars differ in that L. annulatus obtains a high percentage of its prey from the water column, while P. helianthoides primarily feeds on bivalves and echinoids. L, annulatus feeds on 50 or more prey types (Dearborn & Edwards 1984, Dearborn et al 1991, including fish, euphausids, ophiuroids, gastropods, bivalves, crinoids, polychaetes, asteroids, isopods, amphipods and echinoids. Common prey include amphipods and euphausiids caught with the pedicellariae and annuli along the arms (Dearborn et al 1991).…”

“…L, annulatus feeds on 50 or more prey types (Dearborn & Edwards 1984, Dearborn et al 1991, including fish, euphausids, ophiuroids, gastropods, bivalves, crinoids, polychaetes, asteroids, isopods, amphipods and echinoids. Common prey include amphipods and euphausiids caught with the pedicellariae and annuli along the arms (Dearborn et al 1991). Exceptions to the generalist feeding behavior of most antarctic asteroids include the shallow water Granaster nutrix which feeds almost exclusively on small gastropods (Dearborn & Edwards 1984), and Diplasterias brucei which Dayton et al (1974) observed to feed almost entirely on the bivalve Limatula hodgsoni in McMurdo Sound.…”

Feeding ecology of deep-sea seastars (Echinodermata: Asteroidea): a fatty-acid biomarker approach

“…Some forcipulatid asteroids are known for their ability to capture mobile pelagic prey using the crossed pedicellaria on their aboral surfaces (Dearborn et al 1991, Lauerman 1998. Z. longicauda, however, has straight pedicellaria only (Clark & Downey 1992) and it is unknown if these are capable of capturing mobile pelagic prey.…”

Pedicellariae of the crown-of-thorns sea star Acanthaster planci are not an effective defence against fouling

“…Echinoderm pedicellariae have reported functions in capturing particles and mobile prey, such as small crustaceans or fish (Robilliard 1971, Campbell 1973, Chia & Amerongen 1975, Hendler & Franz 1982, Dearborn et al 1991, Emson & Young 1994, Lauerman 1998, and in deterring predators or competing sea stars (Jensen 1966, Lubchenco Menge & Menge 1974, van Veldhuizen & Oakes 1981. Furthermore, echinoid pedicellariae are proposed to protect the surface from settling fouling organisms.…”