Week 17th – 23rd June, 2013
A good few correct answers this week… This week’s Mystery Creature goes by the name of Elephant Fish, Elephantnose Fish or, most commonly, Peters’ Elephantnose Fish (Gnatonemus petersii).
|photo credit: Joachim S. Müller via photopin cc|
Peters’ elephantnose fish is common in certain parts of Africa, found in muddy, slow moving rivers and pools with heavy vegetation. it are nocturnal, preferring to hide away during the day. It grows to about 20 -25 cm in length and is grey/black to brown in colour. The most striking feature of these little fish is their trunk like “nose”, which is not actually a nose at all but an extension of their mouth, or more specifically their chin.
These fish have quite poor vision but can navigate and seek out food very well using active electroreception; they generate small electric fields by flexing muscles in their tails and then detect any interference in the path of these fields. Its “trunk” like mouth extension is covered in more than 500 electroreceptors (which are also found on much of the body) which can detect the feedback signals. The fish moves forward with its “trunk” pointing downwards, passes it back and forth, just like a metal detector. Active electroreception can be likened to echolocation in other animals such as whales and bats. The detail these fish can gleam from their electrical scan of their environments is quite remarkable. In order to process the information they are constantly receiving their brains are very large, larger than that of a human, relative to their overall body size.
In their native environment they feed on small worms and some aquatic invertebrates. They have become popular additions to domestic aquariums though, particularly in America, and appear to accept common fish food in such environments.