Locomotion and contraction in an asconoid calcareous sponge

Abstract

AbstractVarious large‐scale behaviors (e.g., locomotion, shape changes, contractions) have been documented numerous times in intact sponges of the class Demospongiae. However, little is known about such motile events in calcareous sponges (Class Calcarea). Here, we report on whole‐sponge behaviors of the calcareous asconoid sponge Leucosolenia botryoides, as revealed by time‐lapse videos. These behaviors included locomotion and contraction. Locomotion in these sponges appeared as an outward movement (25–130 μm h−1) of the asconoid tubes away from the sponge's center; such translocations were always accompanied by extensive movements of protruding spicules, which appear to act as anchoring hooks for the sponge's translocations. This is the first report of whole‐sponge locomotion in the Calcarea. Contractile waves also were propagated in these sponges at speeds of 50–150 μm h−1, and they involved systemic contraction, then re‐extension of the asconoid tubes. The observations suggest that, like the more complex demosponges, these simple calcareous sponges are capable of adaptive whole‐animal behaviors (changes in flow, shape, and location), which occur in response to environmental stimuli such as crawling intruders.