Pretty predator

Giovanna Fasanelli | VOLUME 29, ISSUE 2

Lionfish are the unchallenged peacocks of the ocean. Their extravagant, almost ostentatious beauty has dazzled divers and aquarists since their discovery. They are members of a large family, the scorpaenidae or scorpionfish, and all are show-stoppers in one way or another, many being masters of cunning, cryptic camouflage.

It is no mystery as to how this infamous group of predators acquired its name, for they all possess venom-tipped spines as their primary defence. Lionfish are grouped into five genera within the subfamily pteroinae. Their natural range is restricted to the Indian and Pacific oceans although, in the last two decades, the common lionfish (pterois volitans) and the Indian lionfish (pterois miles) have established burgeoning populations on reefs in the western Atlantic as a result of aquarium-related releases/escapes. These native ecosystems are now suffering catastrophic devastation at the hand of these two voracious predators.

In their native range, however, lionfish are welcomed treasures to find on any dive or snorkel. The common lionfish is a favourite of many marine enthusiasts, but some of the lesser-known species are no less impressive.

One character, in particular, rivals its larger, more conspicuous cousins in astonishing glamour. Fully grown at just 13cm the twin-spot lionfish (dendrochirus biocellatus) is nothing short of exquisite. As highly secretive, nocturnal hunters that prefer to hide upside-down in caves and under overhangs during daylight hours, these creatures are rarely seen by underwater explorers unless night diving is undertaken. They are found at depths of up to 40m on reefs from Mauritius eastwards to the Society Islands and from Japan southwards to Australia.

Upon close inspection, their outstretched, undulating pectoral fins seem to pulse with waves of colour in patterns that have an alluring, almost hypnotic effect on an observer. The dorsal fin sports two distinctive spots, or ocelli, likely functioning as a communication tool, since they vary in colour intensity from black to faded grey during a variety of intra-species interactions or simply when the fish is excited by prey. They have two long barbels extending out from their upper jaw, which lend an even more unique appearance to this pretty predator.

In stalking a victim, the twin-spot lionfish will either hop along using its pelvic fins or move by engaging its tail. Once a victim has been spotted and is within striking distance, the twin-spot has been observed to shake its head from side to side, rhythmically rattle its fin spines back and forth, and vibrate its lower pectoral fins. Following this interesting war-dance, it then lunges forward and rapidly opens its capacious mouth, sucking in the hapless quarry! Favoured food usually comprises small crustaceans, but may also include smaller individuals of the same species. If faced with a stubborn, territorial challenger, these small packets of fury may attack by biting and stabbing one another with their dorsal spines.

Between their mesmerising beauty, their pugnacious character and their secretive lives, I place this beauty of a lionfish at the top of my list of scorpionfish favourites.

Creature Features