This saltwater bivalve (Ctenoides听ales) goes by quite a few names including 鈥渆lectro-flame scallop,鈥� 鈥渆lectric clam,鈥� and 鈥渄isco clam鈥� and it鈥檚 easy to see why. These animals are vibrantly colored and are among only a couple bivalves that can display a light show. Disco clams light up鈥�flashing 鈥渓ights鈥� along their red mantle to confuse and deter predators. This light is not a form of bioluminescence, in which organisms are able to produce and emit light, but instead is created by highly reflective silica-rich cells on the edge of their mantle tissue. The clam can flex these tissues, exposing and hiding them in quick succession, creating a flashing or strobing effect due to reflection of sunlight through the water. The tissue around these display cells is a vibrant,听reddish-orange hue, while the shell itself is a mottled tan color.
Researcher Lindsey Dougherty, who was a postdoctoral fellow working with the CU Museum鈥檚 invertebrate collections, and her team found that this bright red portion of the mantle is chemically different from the rest of the non-colorful tissue. The bright color is due to, in part, peptide-like compounds that may be slightly noxious and unpalatable to predators. The combination of red color and flashing display could be warning predators that the clam is distasteful. This is a valuable defense mechanism, especially since the mantis shrimp is one of听the disco clam鈥檚 predators.听These shrimp听are known for their ability to break the shell of a clam but, fortunately for听Ctenoides听ales,听they have sensitive eyesight that would not miss these dramatic disco displays. If the light show wasn鈥檛 enough of a deterrent,听Doughtery听found these clams spewed acidic mucus at the shrimp, disabling them for up to 15 minutes under laboratory conditions2.听听
Disco clams are distributed in tropical waters of the Indo-Pacific, where many creatures are brightly colored, thus their display is but one of many flashy shows. Like many coral-dwelling organisms, the disco clam is a rare sight in its habitat. These听molluscs听spawn to reproduce, meaning a male and female will release their gametes into the water for fertilization. Their ability to reproduce is reflective of plankton abundance, as plankton is their primary food source2. Few baby disco clams survive without abundant plankton. With rising ocean temperatures, many species sustained by coral reef habitats are experiencing population declines, including the disco clam. While many of us may be far from an ocean, we should remember that our actions have an impact there. Let鈥檚 keep this party called life on earth going!听听
1. Dougherty, L. F.,听Niebergall, A. K.,听Broeckling, C. D., Schauer, K. L., & Li, J. (2019). Brightly听coloured听tissues in听limid听bivalves chemically deter predators.听Royal Society open science,听6(10), 191298.
2.
Video credit: Lindsey Dougherty and Roy Caldwell