Treasure of the month

December 2016

Rod Angler

This rod angler is our Treasure of the Month for December and a most unusual animal. The females of this species from the rodfish family (Ceratiidae) are the giants among the deep-sea anglerfishes (Ceratioidei). They can grow to over a meter in length and reach a weight of about 10 kg.

In contrast, males are dwarfs, weighing no more than 150 g. Male rodfish live as so-called parasitic dwarf males attached to females. They spawn and die together with their female. The conspicuous whip-shaped "fishing rod" of females is the transformed first hard ray of the dorsal fin, which they use to attract prey. Other distinctive features of rod anglers are their nearly vertical mouths and their small eyes, which are probably non-functional.

This exhibit of Ceratias holboelli from the Museum of Nature Hamburg - Zoology exhibit (temporarily closed to the public due to construction) shows a female with a dwarf male. The pair was captured in 1940 south of Iceland at a depth of 400 meters. The female is probably the largest publicly exhibited specimen of its species.