The macrobenthic community in intertidal sea urchin pits and an obligate inquilinism of a limpet-shaped trochid gastropod in the pits
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Softer rocks in the intertidal zones of southern Japan are occasionally excavated by the rock-boring sea urchin, Echinostrephus molaris, and the pits are often succeeded by non-boring sea urchins, Anthocidaris crassispina and Echinometra tsumajiro after the death of Ec. molaris. Although the rock-boring sea urchin can fold their thin spines and retreat deeply into the pit bottoms, non-boring sea urchins with stouter spines cannot retreat deeply, thus, leaving spaces between their spines and the pit wall. To evaluate the uniqueness of these pits as microhabitats, we conducted an extensive census of biota both inside and outside of the pits occupied by rock-boring and non-boring sea urchins in tidal pools at Shirahama in southern Japan (33°69′51″N, 135°33′58″E). Macrophytes were only observed outside the pits, whereas sessile filter feeders and detritus feeders were found at similar frequencies in all of the microhabitats. The abundance and species richness of algal grazers and carnivores, however, were significantly higher in outside and inside the pits occupied by non-boring sea urchins compared to pits occupied by rock-boring sea urchins. The pit occupied by a non-boring sea urchin was specifically inhabited by a limpet-like trochid snail, Broderipia iridescens, the biology of which is almost completely unknown. Our data suggest that this trochid species is the first example of obligate inquiline with a non-boring pit-inhabiting sea urchin, adapted to the life in the pits, where the limpet benefit by sneaking in the gap between the pit wall and sea urchin spines, escaping from contact with the spines and being protected from attack by predaceous muricid snails.
KeywordsRock-boring sea urchin Broderipia Ecosystem engineer Obligate commensalism Flattening of shell
We thank all the staffs of the Seto Marine Biological Laboratory for supporting our field survey, Ryo Nakayama and Youhei Yamauchi of the Laboratory for technical support, and Kasumi Kondo of Kyoto University for helping with the sampling.
Compliance with ethical standards
This work was supported by Grant-in-Aid for Scientific Research 2015–2019 (15H02420) to MK.
Conflict of interest
We have no conflict of interest.
- Delongueville C, Scaillet R (2009) Illustration de Vitreolina philippi (Ponzi, de Rayneval & Van den Hecke, 1854) sur Paracentrotus lividus (Lamarck, 1816) à Chypre Nord. NOVAPEX/Société 10:100Google Scholar
- Harper E, Morton B (1997) Muricid predation upon an under-boulder community of epibyssate bivalves in the Cape D’Aguilar Marine Reserve, Hong Kong. The Marine Flora and Fauna of Hong Kong and Southern China IV. Hong Kong University Press, Hong Kong, pp 263–284Google Scholar
- Hylleberg J (1994) Phylum Sipuncula. Part 2. Cryptic fauna with emphasis on sipunculans in hump coral Porites lutea, the Andaman Sea, Thailand. Phuket Mar Biol Cent Res Bull 59:33–41Google Scholar
- Killian CE, Metzler RA, Gong Y, Churchill TH, Olson IC, Trubetskoy V, Christensen MB, Fournelle JH, De Carlo F, Cohen S, Mahamid J, Scholl A, Young A, Doran A, Wilt FH, Coppersmith SN, Gilbert PUPA (2011) Self-sharpening mechanism of the sea urchin tooth. Adv Funct Mater 21:682–690CrossRefGoogle Scholar
- Kishu Shimanto Research Group (1972) The Muro Group in the Upperreaches of Koza River in Wakayama Prefecture: The study of the Shimanto Terrain in the Kii Peninsula, Southwest Japan (Part 5). Chikyukagaku (in Japanese) 26:195–204Google Scholar
- Kobayashi N, Tokioka T (1976) Preliminary observatoin on the maturation of the burrowing sea urchin, Echinostrephus aciculatus (A. Agassiz), in the vicinity of Seto. Publ Seto Mar Biol Lab 23:57–62Google Scholar
- Ohgaki SI, Komemoto KI, Funayama N (2011) 3. Comments on selected species. Publ Seto Mar Biol Lab. Spec Publ Ser 11:15–23Google Scholar
- Valentich-Scott P, Dinesen GE (2004) Rock and coral boring Bivalvia (Mollusca) of the middle Florida Keys, USA. Malacologia 46:339–354Google Scholar
- Gordillo S (1998) Trophonid gastropod predation on recent bivalves from the Magellanic Region. Bivalves: an eon of evolution. Paleobiological Studies Honoring Norman D. Newell :251–254.Google Scholar