Bohadschia argus
A sea cucumber with eyespots and defensive Cuvierian tubules.
The leopard sea cucumber, also called the leopardfish or tigerfish, is a species of sea cucumber from the family Holothuriidae. It lives in the tropical Western Indo-Pacific region.
Like most sea cucumbers, *Bohadschia argus* has a roughly cylindrical body. It typically reaches about 36 cm (14 in) in length and weighs between 1.8 and 2.2 kg (4.0 to 4.9 lb), with a maximum recorded length of 60 cm (24 in). Its tough outer body wall is about 10 mm (0.39 in) thick and feels firm and leathery. The upper side is greyish-brown and covered with many yellow eyespots, which give the animal its common name. The underside is usually paler, though some individuals are uniformly brown.
Several rows of tube feet on the underside help it move. Around the mouth at the front end is a ring of black, paddle-shaped feeding tentacles with white fringes. At the rear end, near the anus, are Cuvierian tubules. When disturbed or handled, the sea cucumber ejects these sticky threads, which contain toxins that deter predators and can irritate human skin. *Bohadschia argus* can apparently hybridize with *Bohadschia vitiensis*.
This species lives in shallow tropical waters across the eastern Indian Ocean and western Pacific. It is common on exposed, sandy areas of the seabed around coral reefs, usually at depths of 2 to 10 m (6.6 to 32.8 ft).
As a detritivore, *Bohadschia argus* sweeps sand grains and detritus into its mouth with its sticky tentacles as it moves across the seabed. It gets some nourishment from the biofilm coating the grains.
Pearlfish—specifically *Carapus mourlani* (star pearlfish) and *Encheliophis boraborensis* (pinhead pearlfish)—sometimes live inside the sea cucumber’s coelomic cavity, usually entering head-first through the anus. In a study in the Banda Islands, 15 star pearlfish were found inside a single *Bohadschia argus*. *Carapus mourlani* has a mutualistic relationship with the sea cucumber and will aggressively defend it from the parasitic *Encheliophis boraborensis*, sometimes fighting to the death. The emperor shrimp (*Zenopontonia rex*) is also often associated with *Bohadschia argus* and may help keep it free of ectoparasites.
A new compound called Arguside A, a triterpene glycoside, has been extracted from the sea cucumber’s tissues. This substance appears to be cytotoxic against several types of human tumor cells.
Quick Facts
- Taxon
- Bohadschia argus
Facts from the source article.
Lore & Background
Bohadschia argus has a roughly cylindrical body plan, with a tough, leathery outer body wall about 10 mm thick. Its dorsal side is greyish-brown with numerous yellow eyespots, while the underside is usually paler. It has several rows of tube feet for locomotion and a ring of paddle-shaped, black feeding tentacles with white fringes around the mouth. At the posterior end, Cuvierian tubules at the base of the anus are ejected as sticky threads when disturbed, containing toxins that deter predators and irritate human skin. The species appears able to hybridize with Bohadschia vitiensis.
It inhabits shallow tropical waters of the eastern Indian Ocean and western Pacific, commonly on exposed sandy areas near coral reefs at depths of 2 to 10 m. As a detritivore, it sweeps sand grains and detritus into its mouth using sticky tentacles, obtaining nourishment from biofilm coating the grains.
Symbiotic relationships include pearlfish such as Carapus mourlani (star pearlfish) and Encheliophis boraborensis (pinhead pearlfish) living in its coelomic cavity, entering through the anus. In a study in the Banda Islands, 15 star pearlfish were found in a single sea cucumber. Carapus mourlani has a mutualistic relationship and aggressively defends the sea cucumber from the parasitic Encheliophis boraborensis, sometimes fighting to the death. The emperor shrimp (Zenopontonia rex) is often associated with Bohadschia argus and may help keep it clear of ectoparasites.
Reader's Guide
Bohadschia argus is significant for its role in the coral reef ecosystem as a detritivore, processing sand and biofilm. Its defense mechanism—ejecting toxic Cuvierian tubules—is a notable adaptation against predators. The species also serves as a host for symbiotic pearlfish, with a documented case of 15 star pearlfish living in a single individual, highlighting its importance as a microhabitat. Additionally, a new triterpene glycoside called Arguside A has been extracted from its tissues, which exhibits cytotoxicity against several types of human tumor cells, suggesting potential biomedical significance. Its ability to hybridize with Bohadschia vitiensis adds to its biological interest. The species is commonly found in shallow waters of the Indo-Pacific, making it accessible for study and observation.
Did You Know?
- Bohadschia argus can eject sticky Cuvierian tubules from its anus when disturbed, which contain toxins irritating to human skin.
- A group of 15 star pearlfish (Carapus mourlani) was found living within the body cavity of a single Bohadschia argus in the Banda Islands.
- A compound called Arguside A, extracted from Bohadschia argus tissues, shows cytotoxicity against several types of human tumor cells.
More in Sea Cucumbers and Brittle Stars, Part 2 1-24
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