Mobility and self-righting by a free-living mushroom coral through pulsed inflation

Bert W Hoeksema,Pim Bongaerts

doi:10.1007/s12526-015-0384-y

Abstract

Locomotion and self-righting in an overturned juvenile mushroom coral, Herpolitha limax, was documented and analyzed by the use of time-lapse photography. The coral used a series of rhythmic polyp expansions and contractions to move itself. The complete process of the righting took place within six hours, consisting of a stationary phase, a shuffle phase, a sudden flip-over, and a recovery phase. The mouth of the coral may be used to eject water, which can perhaps be applied as a means of jet propulsion. This report demonstrates that time-lapse photography can be applied to analyze all kinds of behavior in marine invertebrates that move too slow for regular observations.

Highlights

More than 70% (n=55) of all recent mushroom coral species (Scleractinia: Fungiidae) have a free-living adult phase in their life history (Gittenberger et al 2011; Benzoni et al 2012), which is the so-called anthocyathus stage (Wells 1966; Hoeksema 1989)
We present detailed information on a flip-over experiment in which mushroom corals were overturned to document their self-righting technique with the help of time-lapse photography
The coral polyp became deflated and shrank (Fig. 1l). This is the first time that self-righting in free-living corals is documented, analysed and published with the help of timelapse photography

Summary

Introduction

More than 70% (n=55) of all recent mushroom coral species (Scleractinia: Fungiidae) have a free-living adult phase in their life history (Gittenberger et al 2011; Benzoni et al 2012), which is the so-called anthocyathus stage (Wells 1966; Hoeksema 1989). As free-living corals, fungiids are able to colonize all kinds of substrata These include sandy bottoms at>20 m depth, which are usually not inhabited by many other bottom organisms and where mushroom corals can form dense aggregations (Goreau and Yonge 1968; Fisk 1983; Hoeksema 2012). The flip side of a free mode of life is that mushroom corals may accidentally get overturned by other animals or by tumbling down-slope (Jokiel and Cowdin 1976; Hoeksema 1988; Chadwick-Furman and Loya 1992) This is unfavorable because it would incapacitate their ability to capture food, for which an upright position would be most suitable (Hoeksema and Waheed 2012; Mehrotra et al 2015)

Methods

Results

Conclusion