Feeding behavior and morphological adaptations in two sympatric sea urchin species in central Chile

Abstract

ABSTRACT. Loxechinus albus and Tetrapygu niger are 2 sympatric sea urchin species present in the rocky intertidal and subtidal zones of central Chile. In this study we test the hypothesis that the 2 species employ dfferent feeding mechanisms, and that this has resulted in distinct ecological roles for the 2 species. We also analyze structures associated with feeding. Results from field studies indicate that T niger principally consumes benthic algae (i.e. Gelidium spp.) and in doing so clears significantly more primary space than does L. albus. Laboratory experiments confirmed this observation, and demonstrated that T. niger consumes significantly more benthic algae (i.e. Gelidiurn spp.) attached to rock than floating algal pieces (i.e. Lessom'a nigrescens). Small L. albus ( < 3 cm diameter) consume significantly more benthic than floating algae pieces; the reverse is true for large (> 3 cm diameter) individuals. While oral podia in both species are modified terminally to form suckers, only L. albus possesses such modifications on aboral poda. Additionally, in T. niger the pyramids of Aristotle's lantern are roughly twice as long as those in L, albus. We discuss the possible ecological roles of each species with reference to the structure of intertidal communities.

Enlarged lantern size in similar-sized, sympatric, sibling species of Strongylocentrotid sea urchins: from phenotypic accommodation to functional adaptation for durophagy

“…These results are consistent with a hypothesis of enlarged lantern size being a functional specialization for durophagy, and is apparently the first evidence of a relationship between trophic morphology and diet in regular sea urchins. The hypothesis that enlarged lantern size is an adaptation for durophagy is also consistent with studies of sympatric sea urchins from different genera, where the species with the largest lantern occupies microhabitats with a scarcity of soft food (Contreras and Castilla 1987;Fernandez and Boudouresque 1997). However, contrary to the assumption of a direct relationship between lantern size and feeding capacity in strongylocentrotid sea urchins (Lawrence et al 1995), there was also a large inter-specific difference in feeding capacity The slope and elevation of the logarithmic allometric equation, ln(Y) = ln(a) + bln(X), were determined using standardized major axis (SMA) estimation.…”

Role of two co-occurring Mediterranean sea urchins in the formation of barren from Cystoseira canopy

“…(percent wet weight (g)) at the end of the experiment. Factors include: "Urchin" (Ur; three levels: P. lividus, A. lixula and no urchins), fixed, and "Aquarium" (Aq; three levels), random and nested in Ur (n ¼ 3 and/or sessile invertebrates from hard substrata by means of the powerful teeth of the Aristotle's lantern, and (3) capture of drift algae, 'drift-trapping behaviour', by the ambulacral tube feet and spines and the subsequent transport of this material to the mouth (Conteras and Castilla, 1987;Lawrence, 2013). Regarding this, the two urchin species differ morphologically: P. lividus has shorter and denser spines, more extendible aboral tube feet and a weaker Aristotle's lantern than A. lixula and it is likely that such differences affect their feeding behaviors Flammang, 2005, 2007).…”

Consumption of drift kelp by intertidal populations of the sea urchin Tetrapygus niger on the central Chilean coast: possible consequences at different ecological levels

“…Previous studies have considered this species unable to use drift algae as an important food item (Vásquez 1986, Contreras & Castilla 1987, although this could be partly overcome by aggregation, i.e. formation of highdensity groups in zones with strong bottom currents (Vásquez & Buschmann 1997).…”

“…This urchin mainly consumes turfing algae (Contreras & Castilla 1987). Moreover, it has been considered unable to use drift algae as an important food item because it lacks the morphological structures necessary to capture this kind of resource (Vásquez 1986, Contreras & Castilla 1987. Vásquez (1993) has, however, suggested that this morphological deficiency could be overcome, in part, through the aggregation of individuals, which increases the probability of retaining drift material among spines.…”

“…This urchin mainly consumes turfing algae (Contreras & Castilla 1987). Moreover, it has been considered unable to use drift algae as an important food item because it lacks the morphological structures necessary to capture this kind of resource (Vásquez 1986, Contreras & Castilla 1987.…”