Monocirrhus polyacanthus

Monocirrhus polyacanthus

Also known as the South American Leaf Fish, Monocirrhus polyacanthus is another great example of mimicry, deception and evolution. It has evolved to utilise false markings and behavior in an unusual but brilliant form of aggressive mimicry. In terms of its morphological features; it can have a range of colourations; ranging from orange-yellow to brown with various markings that give this species the appearance of a dead leaf. This colouration is dependent of its surroundings. It has transparent pectoral fins that allow this species to stay afloat without breaking the illusion. The pectoral and caudal fins developed early in the species life. Walker (2004) states that this is due to standard maneuvering and “start movements” commonly associated to predation strikes. Its behavior is simply to drift around and slowly approach unsuspecting prey. This false behavior masks its predatory nature as well as strengthening the illusion of a dead leaf. However, once they come into range of the prey, they utilise predation strikes in order to catch their prey. This species possesses an extendable and large mouth that creates a vacuum that sucks the prey in. Because of its hunting nature, prey may be consumed between large periods of time. Its mouth morphology allows it to consume prey that are proportionally large. Catarino & Zuanon (2010) state that the combination of its morphology and visually effective false markings allow this species to consume the large as well as the fast moving prey.

Figure 1: Monocirrhus polyacanthus camouflaged within dead leaves. Photographer: Mühlacker (2015).

As seen in the previous posts; mimicry and deception in animals is a useful technique that can utilized defensively, aggressively or a combination of both. It ranges from looking like another species, sounding like another species and behaving in deceptive manners just to name a few. However, these species have evolved to be like this, they may not have been like this originally and it did not happen overnight. Over the new few posts I will attempt to present a simple explanation of how evolution works and how some of these species have come to such masters of mimicry and deception.

References

CATARINO, M. F., & ZUANON, J. (2010). Feeding ecology of the leaf fish Monocirrhus polyacanthus (Perciformes: Polycentridae) in a terra firme stream in the Brazilian Amazon. Neotropical Ichthyology. 8, 183-186.

Mühlacker, M. (2015). Monocirrhus polyacanthus camouflaged within dead leaves. http://medienwerkstatt-online.de/lws_wissen/vorlagen/showcard.php?id=21359&edit=0. Retrieved: 13/05/2015

WALKER, J. A. (2004). Kinematics and Performance of Maneuvering Control Surfaces in Teleost Fishes. IEEE JOURNAL OF OCEANIC ENGINEERING. 29, 572-584.