Pedum spondyloideum (Gmelin 1791)

The pectinid scallop Pedum spondyloideum occurs almost exclusively on massive coral colonies of the genus Porites. These scallops have reduced the effects of recent heavy levels of predation by the starfish Acanthaster planci on their coral hosts on the Great Barrier Reef. Scallops repel foraging starfish and other echinoderms on contact by repeated expulsion of jets of water. In coral populations subject to heavy predation pressure, this paramutualistic behavlour has resulted in significantly greater survival of host Porites in comparison with congeners without scallops. The survival of corals protected by scallop populations may be important in enhancing recovery and preserving the population structures of these long-lived species. The scallop's expellent water jets function primarily in the removal of wastes. Pedum spondyloideum's secondary application of the jets against A. planci and other foraging organisms may thus exemplify an exapted means of host defence. (DeVantier and Endean, 1988.)

拟海菊足扇贝（学名：Pedum spondyloideum，台湾称海菊海扇蛤），是莺蛤目海扇蛤科Pedum的一种。主要分布于新加坡、马来西亚、中国大陆、台湾，常出现在潮下带浅水域、滨珊瑚的块状珊瑚头中，营穴居生活。

littoral-below littoral