A Favourite Parasite

Dendromonocotyle dark field image 430W

South Australian Museum’s Parasitology Collection Manager Dr Leslie Chisholm has a favourite parasite genus, Dendromonocotyle.

Dendromonocotyle is a genus of flatworm, only 1.5–2 mm long, that lives on the skin of stingrays.The tiny worms are beautifully camouflaged as a result of eating skin cells from the rays — this causes them to turn exactly the same colour as their host animal. Indeed, they are so well hidden that even cleaner fish (which normally pick parasites off the skin and gills of fish and rays in the wild) leave them behind.

Although they don’t usually pose a health problem to rays living in the wild, Dendromonocotyle species can create issues when they reproduce to very high numbers on rays kept in aquaria or other captive environments. Other parasites can similarly explode in population size and create problems when wild fish are corralled for commercial fishing.

 

Dendromonocotyle lasti from South Australian Museum on Vimeo.

 haptor of Dendromonocotyle urogymniAttachment organ of Dendromonocotyle urogymni.

 

Dendromonocotyle ardea haptorAttachment organ of Dendromonocotyle ardea.

 

Two live DendromonocotyleTwo live adult Dendromonocotyle specimens from a ray off Stradbroke Island, Queensland. The tiny brown objects are tetrahedral eggs laid by the parasites.