''Cymothoa elegans'' is a species of

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

isopod Isopoda is an Order (biology), order of crustaceans. Members of this group are called isopods and include both Aquatic animal, aquatic species and Terrestrial animal, terrestrial species such as woodlice. All have rigid, segmented exoskeletons ...

in the genus '' Cymothoa''. It has rarely been recorded, with all records coming from the north coast of

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

. Like other ''Cymothoa'' species, ''C. elegans'' is a fish

ectoparasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

Description

''C. elegans''

exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...

and

chitinous Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chitin are pr ...

. It consists of overlapping

tergite A ''tergum'' (Latin for "the back"; : ''terga'', associated adjective tergal) is the Anatomical terms of location#Dorsal and ventral, dorsal ('upper') portion of an arthropod segment other than the head. The Anatomical terms of location#Anterior ...

s that provide protection and flexibility. The body is dorso-ventrally flattened, or flattened in the vertical axis (top to bottom), which is common for marine isopods. They have jointed limbs with non-specialized legs (none modified for purposes other than

movement Movement may refer to: Generic uses * Movement (clockwork), the internal mechanism of a timepiece * Movement (sign language), a hand movement when signing * Motion, commonly referred to as movement * Movement (music), a division of a larger co ...

Distribution

This species has been recorded off the north coast of Java, Indonesia; in the

Java Sea The Java Sea (, ) is an extensive shallow sea on the Sunda Shelf, between the Indonesian islands of Borneo to the north, Java to the south, Sumatra to the west, and Sulawesi to the east. Karimata Strait to its northwest links it to the South Ch ...

. More broadly, parasitic isopods are more commonly found in tropical and subtropical locations.

Biology

''C. elegans'' is an

, living outside their

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County * Host Island, in the Wilhelm Archipelago, Antarctica People * ...

's tissues. It often attacks the

mouth A mouth also referred to as the oral is the body orifice through which many animals ingest food and animal communication#Auditory, vocalize. The body cavity immediately behind the mouth opening, known as the oral cavity (or in Latin), is also t ...

of fish, the lip, inside the mouth cavity, or the

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

. These isopods may spend their entire life on one host. Because these parasites are blood-sucking, they move their food into their esophagus, which is then passed to the stomach (Ruppert). They have adapted mouthparts ideal for clinging and sucking for holding on to their hosts.

Reproduction

Eggs are held by the female in their brood pouch either inside or outside the body. It is unclear whether or not ''C. elegans'' are

hermaphrodite A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

s, born male and develop into females later in life. This is because of limited specimens, although it is common for other parasitic isopods.

References

Cymothoida Crustaceans described in 1885 {{Isopod-stub