''Molicola horridus'' is a species of

tapeworm Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestodar ...

. The adult worm is found in the

spiral valve A spiral valve or scroll valve is the corkscrew-shaped lower portion of the intestine of some sharks, Acipenseriformes (sturgeon and paddlefish), rays, skates, bichirs, Lepisosteiformes (gars), and lungfishes. A modification of the ileum, the ...

in the lower part of the intestine of the

blue shark The blue shark (''Prionace glauca''), also known as the great blue shark, is a species of requiem shark, in the family Carcharhinidae, which inhabits deep waters in the world's temperate and tropical oceans. Averaging around and preferring co ...

(''Prionace glauca''). The larvae are found infesting the livers and muscles of ray-finned fishes such as the

ocean sunfish The ocean sunfish or common mola (''Mola mola'') is one of the largest bony fish in the world. It was misidentified as the heaviest bony fish, which was actually a different species, ''Mola alexandrini''. Adults typically weigh between . The spe ...

(''Mola mola''), and the

spot-fin porcupinefish The spot-fin porcupinefish (''Diodon hystrix''), also known as the spotted porcupinefish, black-spotted porcupinefish or simply porcupinefish, is a member of the family Diodontidae. Description The spot-fin porcupinefish is a medium-sized fish ...

(''Diodon hystrix''). This tapeworm has been found parasitising sharks from France, the Mediterranean region, Brazil, Canada, India, Japan and New Zealand.

References

Cestoda Animals described in 1841 {{Cestoda-stub