In situ measurements of righting behavior in the common sea urchin Lytechinus variegatus: the importance of body size, substrate type, and covering material

RC Challener,JB McClintock

doi:10.3354/ab00669

Abstract

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 26:33-40 (2017) - DOI: https://doi.org/10.3354/ab00669 In situ measurements of righting behavior in the common sea urchin Lytechinus variegatus: the importance of body size, substrate type, and covering material R. C. Challener1,*, J. B. McClintock2 1Bellarmine University, Department of Biology, Louisville, KY 40205, USA 2University of Alabama at Birmingham, Department of Biology, Birmingham, AL 35294, USA *Corresponding author: rchallener@bellarmine.edu ABSTRACT: Righting behavior has been used extensively in laboratory studies of sea urchins as an indicator of stress under various environmental conditions. In situ measurements of the natural righting response of sea urchins would serve to place such laboratory measurements in an ecological context as well as potentially validate laboratory control conditions. We investigated the righting response of the sea urchin Lytechinus variegatus in seagrass and sand bottom habitats of Saint Joseph’s Bay, Florida. Field-measured righting times (other than the exception mentioned below) in L. variegatus were similar to those measured in laboratory studies. Moreover, as seen in multiple sea urchin species in laboratory studies, smaller individuals exhibited significantly shorter righting times than larger individuals. Importantly, sea urchins lacking covering material (shell material, seagrass blades) that were placed on open sand patches took significantly longer to right than those with covering material placed on sand patches. Our field observations indicate the importance of sea urchin size, substrate type, and the presence or absence of covering materials when making righting measurements in the laboratory or the field. Our findings also suggest that higher water velocities facilitate righting, as at higher flows on sand patches, the presence/absence of covering material no longer significantly impacted righting time. These findings are ecologically important as they indicate that, under certain natural conditions (sand substrate, low availability of covering materials and low water velocities), L. variegatus that are displaced onto their aboral side are more vulnerable to predation. KEY WORDS: Righting response · Covering behavior · Soft bottom · Echinodermata · Echinoidea Full text in pdf format PreviousNextCite this article as: Challener RC, McClintock JB (2017) In situ measurements of righting behavior in the common sea urchin Lytechinus variegatus: the importance of body size, substrate type, and covering material. Aquat Biol 26:33-40. https://doi.org/10.3354/ab00669 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 26. Online publication date: February 21, 2017 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2017 Inter-Research.

Highlights

Echinoderms are widely known for their ability to right themselves from an aboral position (Hyman 1955, Reese 1966)
In our 2014 experiment examining the potential impact of body size and the presence or absence of covering material on righting in Lytechinus variegatus within a patch of seagrass, we detected no significant interaction effect between body size and covering on righting (Fig. 1, 2-way ANOVA, p = 0.063, df = 1, 112)
In our 2014 experiment examining the potential impact of covering material and substrate type on righting in large L. variegatus, we found no significant correlation between body size and righting time, indicating that the size of sea urchins in these experiments did not affect righting times (Spearman’s correlation coefficient analysis, p > 0.254 for all 4 treatments)

Summary

Introduction

Echinoderms are widely known for their ability to right themselves from an aboral position (Hyman 1955, Reese 1966). This righting behavior usually involves the coordinated movements of tube feet and spines (Lawrence 1976a) and is thought to be a simple neurological reflex (Reese 1966, Binyon 1972). The righting response has been exploited in laboratory studies, with asteroids and echinoids, as a measure of stress under environmen-. Assessing righting responses under natural conditions would permit comparisons with laboratory-based righting times. Such knowledge has the potential to validate laboratory studies, as well as provide valuable information on ecologically relevant righting times. To our knowledge, righting behavior has never been measured for any echinoid or asteroid under natural conditions in the field

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