Brooding and development of Anasterias minuta (Asteroidea: Forcipulata) in Patagonia, Argentina (original) (raw)
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The relation between feeding and reproduction in Anasterias minuta (Asteroidea: Forcipulata)
Marine Biology Research, 2007
Anasterias minuta is an oral-brooding sea star and one of the main predators of intertidal benthos in Patagonia, Argentina. The aims of this study were to: (1) assess the temporal pattern of feeding and brooding, (2) evaluate the effect of body size, tidal height and temperature on feeding and brooding, (3) evaluate temporary changes in digestive and sexual organs and (4) investigate the relationships between the predatory and brooding activities. Females do not feed during the brooding period. Spawning proceeded during March. The brooding period was from March to November, with a maximum in May. The population feeding rate varied seasonally, with a maximum in December and a minimum in May. The feeding rate was positively related to water temperature and sea star size; but not with tidal height. An annual cycle exists for pyloric caeca weight in both sexes; lowest values were found during winter, due to brooding female starvation, and a possible decrease in feeding rate of non-brooding females and males. No inverse relationship was found between the pyloric caeca and gonad weights in females, but a lag of 1 month was observed in males, being the maximal pyloric caeca development before the maximum gonad weight, suggesting nutrient translocation.
Revista de Biología Tropical, 2017
The brooding sea star Anasterias antarctica is distributed from the coast of Patagonia to the northern Peninsula of Antarctica. In the Beagle Channel, the females of A. antarctica brood their eggs for seven months and do not feed during this period. The endoparasite Dendrogaster argentinensis (Crustacea: Ascothoracica) causes castration in several species of Anasterias. We randomly collected four samplings of adults in May, August and October (brooding period) and January (non-brooding period). The gonad (GI) and pyloric caeca index (PCI) were calculated as organ wet weight (g) x 100/total wet weight (g). Each individual was sexed by microscopic examination of the gonads. Sex ratio, brooding females/non-brooding females and mature females/non-mature females ratios was 1:1. The male GI reached maximum values in January, when most individuals were sexually mature. The GI of non-brooding females reached its maximum during October when it was significantly higher than those from broodin...
Rev. Biol. Trop, 2008
The feeding ecology of the brooding sea star Anasterias minuta within tide pools was examined in Central and South Patagonia. 8 470 observations of sea stars were made. A. minuta does not feed while brooding. It consumes a wide range of prey, including molluscs and crustaceans, and can be regarded as a generalist or opportunistic predator. The purple mussel Perumytilus purpuratus was the most abundant prey item (57.6%). Other important prey were the gastropod Pareuthria plumbea, the isopod Exosphaeroma lanceolatum and the mussels Aulacomya atra atra and Mytilus edulis platensis. The proportion of sea stars feeding on sessile prey increases with sea-star size. A significant positive correlation was found between the size of the sea star and the size of the most frequent prey. The diet was fairly constant throughout the year, but diet composition differed between sites, shore level and sea-star size. The diversity of prey consumed by A. minuta was highest on the semi-exposed coast of Caleta Cordova Norte during the temperate season on the infralittoral fringe. A. minuta does not eat prey in proportion to its abundance beneath rocks within tide pools at the infralittoral fringe. Generally, the sea star consumed P. purpuratus and the gastropod P. plumbea more than other prey, even when they were not the most abundant prey present. At the midlittoral zone of the semi-exposed coast of Caleta Cordova Norte, the sea star feeds on prey species accordingly to their abundance. Larger P. purpuratus and E. lanceolatum were eaten disproportionately more often. A. minuta may have an opportunistic feeding strategy, taking unattached, wave-washed mussels when available rather that attached mussels. Consequently, it may have a variable impact on the community structure.