Masqueraders of the deep seas – Scorpaenidae in Indian waters
The family Scorpaenidae (Scorpionfish) is one most divers get acquainted with quite early in their diving. Instructors repeatedly remind students to look out for the venomous and very conspicuous lionfish. Dive buddies exchange excited underwater gesticulations when a well-camouflaged scorpionfish is spotted on the reef. And rightfully so! The Scorpaenidae family includes many of the world’s most venomous fish species. The two groups most likely to be encountered in Indian waters are the lionfish and scorpionfish.
Lionfish are probably some of the most easily recognised and photographed fish amongst divers. They are flamboyant, with bold stripes, usually ranging from bright orange to a deep maroon. A series of long dorsal spines complement the dramatically elongated radiating spines of their pectoral fins. All in all, they are visually magnificent. However, these dazzling good looks come with a clear message – lionfish are very capable of defending themselves. Their dorsal spines can deliver a painful ‘sting’. This deters many predators that could otherwise easily out-swim and capture this generally slow-moving fish. In humans, the venom results in pain that can vary from uncomfortable to very intense, accompanied by nausea, fever and dizziness. In some instances, lionfish venom has proven fatal to children, people with weak immune systems, or those who have an allergic reaction to it.
You can’t let that deter you from observing these beautiful creatures on the reef. Lionfish are confident in their ability to defend themselves and will allow divers to get quite close to them. Some of them can be quite curious and will even swim in for a better look. They are harmless if not touched, and their ‘I’m-not-afraid-of-you’ attitude allows a diver to really observe them closely. These bizarre looking fish are skilled hunters, mostly active in the first half of the day. They swim close to the reef floor, along with the sides of coral heads and beneath overhangs, looking for smaller fish, invertebrates and mollusks. Often you can see this predator hanging almost motionless, displaying incredible control, close to a school of glassfish. With a thrust of its large pectoral fins and a simultaneous expansion of its mouth, the lionfish creates a suction in the water, swallowing its prey whole!
Appearance wise, scorpionfish couldn’t be more different than their lionfish cousins. Their compressed bodies are designed to allow them to perch low among the coral and rock. Tassels, flaps and hair-like spines adorn the skin, adding to the cryptic appearance of these fish. The ability to change colour to blend in with their environment completes the camouflage of these ambush predators. Unlike lionfish, divers encounter scorpionfish by actively looking for them or stumbling upon them by chance on the reef. A scorpionfish is rarely seen in motion unless disturbed. Instead, it sits stock-still and does everything it can, to blend into its environment. It stays motionless, sometimes in the same area, for weeks at a time, waiting for unsuspecting fish to swim past. Like the lionfish, the scorpionfish is able to create a suction field in the water by rapidly expanding its buccal cavity. Fish are swallowed whole before they even become aware of the predator’s presence!
The red colours on this Tassled or Bearded Scorpionfish (Scorpaenopsis oxycephala) are highlighted by the use of an underwater strobe. Without artificial light, these fish look very much like the algae covered rocks they perch on.
Although there is no overt advertising of danger in this group of fish, they too possess venomous spines in the dorsal, anal and pelvic fins. Scorpionfish will generally swim away just before being touched by the straying hand or fin of a careless diver. But their last defensive action is to raise their dorsal spines that are otherwise lowered to contribute to their rock-like appearance. This can result in a painful wound with reactions known to be worse than those associated with lionfish venom. Holding the wound in hot water helps to alleviate the pain.
Informally known as the Common lionfish (Pterois volitans) this sub-adult is in between the darker colour phase of the juveniles (still visible on the dorsal spines and fins) and the bolder orange phase of the adults.
Both lionfish and scorpionfish make excellent subjects for underwater photography. Scorpionfish will sit still enough to allow macro photographs of their eyes and fringed lips. Lionfish make incredible models in wide-angle images of the reef. Catching them yawning to stretch out their highly expandable mouths is a rare, but an amazing sight. Both fish are a reminder that good buoyancy and careful diving are a must, for the health of the reef and the enjoyment of its human visitors.
This Devil scorpionfish (Scorpaenopsis diabolus) was photographed just offshore, in chest-high water, in a sandy lagoon off an island in the Lakshadweep chain. Its venomous dorsal spines are clearly visible.
Originally published in Feb 2015 issue of Saevus Magazine
Read also: Underwater Heaven: Havelock (Andaman)
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