Sharp-point Fish Clinger, Nerocila acuminata

Sharp-point Fish Clinger, Nerocila acuminata, Aster. Isopod provided by the commercial fishermen of the greater Los Cabos area, January 2012. Size 2.6 cm (1.0 inch). Identification courtesy of Dr. Julianne Passarelli, Cabrillo Marine Aquarium, San Pedro, California.

Phylogeny:  The Sharp-Point Fish Clinger, Nerocila acuminata (Schioedte & Meinert, 1881), is a common ectoparasite that is a member of the Cymothoidae Family of Ectoparasite Isopods. The genus Nerocila is one of thirty-eight genera in this family, and there are forty-one species in this genus. The Sharp-point Fish Clinger is known in Mexico as Puntiagudo Adherito. The genus name Nerocila is an anagram of the name Caroline by the British zoologist William Leach. The species name acuminata comes from the Latin word meaning “pointed” or “sharpened”.

Morphology: Sharp-Point Fish Clingers are dark brown dorsally and cream colored ventrally. They have symmetrical, ovate, flattened, bodies. The abdomen tapers smoothly from the thorax.  The telson is broad and extends out further than the rest of the abdomen. The head is fused with the first of seven thoracic segments, followed by a a six-segment abdomen. One pair of thoracic appendages is modified into mouth parts. The eyes vary in size from very small to moderately large. They have long legs with pointed tips that are utilized for attachment to the skin of their host fish. Sharp-Point Fish Clingers reach a maximum of 3.0 cm (1.2 inches) in length.

Habitat & Distribution:  The Sharp-pointed Fish Clinger, as the common name suggests,  attaches itself to the skin or base of the fins of fish, including anchovy, flounder, leather jack and surfperch. They are found from the surface to depths of 103 m (338 feet), though some sources extend this depth to beyond 200 m (656 feet). Sharp-pointed Fish Clingers are a tropical to subtropical Eastern Pacific and Western Atlantic species. They reside in all Mexican waters of the Pacific Ocean, Gulf of Mexico, and Caribbean.

Diet: Sharp-Point Fish Clingers are ectoparasites that feed on the blood and tissues of their hosts causing tissue damage, blood loss, and secondary bacterial infections. The Sharp-Point Fish Clinger is not host specific and is commonly found attached to various commercial fishes such as anchovies, flounder, groupers, jacks and perch.

Predation: There is very little documentation of predation on Sharp-Point Fish Clingers. Other species in this genus are prey for specialized cleaner fish and cleaner shrimp.

Reproduction:  Sharp-Point Fish Clingers, unlike most cymothoid isopods, are gonochoric (male or female for life). They reproduce sexually and are viviparous, with females incubating fertilized eggs within a ventral marsupium. The manca (post-larval, immature juvenile stage) are released from the female’s brood pouch as non-parasitic, free-swimmers that actively seek out host fish. Upon attachment to a host, the manca molt into juveniles, which mature into adults.

Ecosystem Interactions: The behavioral study of Sharp-Point Fish Clingers is difficult as the majority are taken via bottom trawls and they commonly abandon their hosts before the trawl reaches the surface. Very little is known as to their interaction with other species, other than their host fish.

Human Interactions:  Sharp-Point Fish Clingers have no significant impact on human activities. Their affect on fisheries is minimal. The effect of isopods on humans if consumed is unknown, but is generally considered safe. From a conservation perspective they have not been formally evaluated however they have are common with a fairly wide distribution and should be consider to be of Least Concern.

Synonym:  Pterisopodus bartschii