Florida manatees Trichechus manatus latirostris actively consume the sponge Chondrilla caribensis.

William Fitt

doi:10.7717/peerj.8443

Abstract

The Florida manatee (Trichechus manatus latirostris Linnaeus 1758) actively selects and consumes the “chicken-liver” sponge Chondrilla caribensis. Manatees ate over 10% of C. caribensis on a sample dock, mostly from pylons that received no direct sunlight. Since manatees reportedly eat mostly seagrasses and algae, it was thought that the chlorophyll-a content of the symbiotic cyanobacteria in C. caribensis might be correlated to the amount eaten; however the correlation was not significant (P > 0.05). C. caribensis has variable chemical defenses and round spherasters (spicules), but these do not appear to be effective deterrents to predation by manatees. This is the first direct evidence that manatees actively seek out and consume a sponge.

Highlights

IntroductionFlorida manatees (Trichechus manatus latirostris) are generally considered to be strictly herbivorous mammals (e.g., seagrasses, algae, seeds, acorns; O’Shea, 1986; Guterres-Pazin, Rosas & Marmontel, 2012), only incidentally consuming invertebrates or fish (Powell, 1978)
Florida manatees (Trichechus manatus latirostris) are generally considered to be strictly herbivorous mammals, only incidentally consuming invertebrates or fish (Powell, 1978)
This paper describes intentional feeding on the sponge C. caribensis by the Florida manatee T. manatus latirostris

Summary

Introduction

Florida manatees (Trichechus manatus latirostris) are generally considered to be strictly herbivorous mammals (e.g., seagrasses, algae, seeds, acorns; O’Shea, 1986; Guterres-Pazin, Rosas & Marmontel, 2012), only incidentally consuming invertebrates or fish (Powell, 1978). In spite of the fact that stomach and fecal analyses find mostly seagrasses and algae, there have been a few instances where manatees have been observed to eat invertebrates (e.g., Courbis & Worthy, 2003). Tunicates, bivalves, gastropods, crustaceans, polychaetes, other small invertebrates and fish have been ingested by manatees and dugongs (Powell, 1978; Reeves, Tuboku-Metzger & Kapindi, 1988; Anderson, 1989; O’Shea et al, 1991; Preen, 1995; Courbis & Worthy, 2003; Guterres-Pazin, Rosas & Marmontel, 2012; Vélez-Juarbe, 2014). Spicules of sponges seen in necropsy samples obtained from manatee carcasses are generally considered incidentally ingested with seagrasses and algae (e.g., Allen et al, 2017). Symbiotic cyanobacteria conduct photosynthesis, fix nitrogen, and metabolize ammonia (oxidizing it to nitrate)

Methods

Results

Discussion

Conclusion