A juvenile Peacock Razorfish (Iniistius pavo) is repeatedly diving into the sand. These juveniles mimic seaweeds, plant debris, or leaves to avoid predation. This form of mimicry, where an animal masquerades itself as a non-living model regarding the form, colour, and posture of its surroundings to avoid being noticed by predators that rely on sight, is not a form of mimicry but a form of camouflage called mimesis (from the ancient Greek “mímēsis,” meaning imitation). Mimicry is a form of aposematism (see link at the bottom of this vlog post). When an animal tries to resemble a plant or a part of a plant, it is called Phytomimesis, such as in the case of the juvenile Peacock Razorfish imitating a drifting leaf.
Juvenile Peacock Razorfish are not the only fish that apply this form of disguise; the juveniles of the Circular Spadefish (Platax orbicularis) also mimic dead leaves. The other two forms of mimesis are zoomimesis and allomimesis. Zoomimesis is when one animal mimics another animal for camouflage purposes.
Good examples of this masquerade in the underwater world is to be found in several members of the Frogfish family; the Painted Frogfish (Antennarius pictus) almost perfectly match the color and texture of some sponges, and the black hairy variation of the Striated Frogfish (Antennarius striatus) is difficult to spot among a herd of black urchins (sea urchins in a group are called a herd).
When an animal resembles a lifeless object, it is called Allomimesis. The Reef Stonefish (Synanceia verrucosa), who looks like a stone or rock, although quite large in size, is the perfect example of a fish that falls into this category of mimesis.
The first two spines of the Peacock Razorfish’s dorsal fin, just above the fish’s head, form a separate fin. In juveniles, this separate fin, resembling the petiole or stalk of a dead leaf, shortens when the fish grows to adulthood.
In addition to being excellently camouflaged, they are very prudent as well: at the first sign of danger, they hide underneath the sand, where they also sleep at night.
Adults of the Peacock Razorfish can reach a total length of 35 cm/14 inches. This solitary benthic wrasse is mainly found on the open and sandy areas where the substrate consists of fine to loose, coarse sand near coral reefs to a depth of 20 m/66 ft or so.
The Peacock Razorfish is quite a common species and inhabits the shallow waters of the Indo-Pacific from Africa’s Eastern coast (including the Red Sea) over Australia, Indonesia, and French Polynesia to Central America.
Because they are known to spend hours under the sand, it was sheer luck to find and film a specimen that performed a little “dive-in-the-sand” show. Most times they duck away and only arise when the potential threat (the observing diver) has vanished.
The movement of the sand pebbles and grains when the little Peacock Razorfish dived into the loose substrate was enhanced by adding a gravelling sound in post-production.
This short underwater videoclip has been filmed in Mauritius 🇲🇺
For a more in-depth description about aposematism please go to our vlog post 111 or click on this link: https://www.beyondscuba.com/post/inimicus-lll-aposematism
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