Antennarius commerson

Lore & Background

Commerson's frogfish was first formally described in 1798 as Lophius commeron by French naturalist Bernard Germain de Lacépède, with its type locality given as Mauritius. Within the genus Antennarius this species belongs to the Antennarius pictus group. The 5th edition of Fishes of the World classifies the genus Antennarius in the family Antennariidae within the suborder Antennarioidei and order Lophiiformes, the anglerfishes. Its specific name honours Philibert Commerçon, the French naturalist whose note Lacépède used to describe this species, although the name is often erroneously attributed to Pierre André Latreille in 1804.

Commerson's frogfish grows up to 38 cm in total length. Like other members of its family, it has a globular, extensible body. Its soft skin is covered with small dermal spinules and partially covered with a few small, wartlike protuberances, some variably shaped, scab-like blotches, and a few small eye spots reminiscent of the holes in sponges. Its large mouth is prognathous, allowing it to consume prey as large as itself. Its coloration is extremely variable, as this species tends to match its environment. Frogfish can change their coloration in a few weeks, but the dominant coloration goes from grey to black, passing through cream, pink, yellow, red, and brown, and also usually with circular eye spots or blotches that are darker than the background.

The first dorsal spine, the illicium, is modified for use as a fishing rod. Its extremity is endowed with a characteristic esca (lure), which resembles a small fish or shrimp with a pinkish to brownish coloration. The illicium is twice the length of the second dorsal spine and is often darkly banded. The second dorsal spine is practically straight and is mobile, the third one is bent towards the back of the body, and both are membranously attached to the head. They are well separated from each other and also from the dorsal fin.

Reader's Guide

Commerson's frogfish is a significant species within the family Antennariidae due to its large size and extreme color variability, which allows it to blend into diverse environments. Its ability to change coloration over a few weeks, ranging from grey to black through cream, pink, yellow, red, and brown, makes it a notable example of adaptive camouflage. The species is also distinguished by its modified first dorsal spine, the illicium, which serves as a fishing rod with a lure that resembles a small fish or shrimp. This adaptation is key to its predatory behavior as a voracious carnivore that attacks any small animals passing within range, including other fish and even congeners. The species has a benthic and solitary lifestyle, gathering only during mating, after which the female may kill or eat the male if he stays close. Its distribution spans tropical and subtropical waters from the Indian Ocean to the eastern coasts of the Pacific Ocean, typically found in lagoons and sheltered rocky and coral reefs, often associated with big sponges, underwater ropes, or jetty pillars down to 70 meters deep. Juvenile specimens can be confused with related species Antennarius maculatus and Antennarius pictus, but distinguishing features include fin margins, skin warts, and eye spot patterns.

Did You Know?

• Commerson's frogfish was first described in 1798 as Lophius commeron by Bernard Germain de Lacépède.
• Its specific name honours Philibert Commerçon, though it is often erroneously attributed to Pierre André Latreille in 1804.
• The female can kill or eat the male if he stays close after fertilization.