Scorpaenidae

Overview

The scorpionfishes have compressed bodies often attired with fleshy, dermal flaps. They have large, heavily ridged and spined heads, one to two opercular spines, and three to five preopercular spines. The single dorsal fin is often notched, and they have 11 to 17 dorsal spines, 8 to 17 soft rays, one to three anal spines, one pelvic spine, and large pectoral fins. Scorpionfishes either have cycloid and/or ctenoid scales, or no scales at all.

They are best known for their venom glands, which are associated with the fin spines. The 3 subfamilies that are best represented on coral reefs are the Scorpaeninae (over 150 species), the Pteroinae (with 16 species), and the Synanceinae (with 10 species). The latter subfamily includes the most venomous fishes in the sea—the stonefishes. Most of the scorpionfishes are benthic, sluggish, and masters of disguise and deception. They typically exhibit chromatic characteristics that enable them to disappear against the substrate.

Many of the boldly colored species, such as the lionfishes and some members of the genus Rhinopias, appear to be exceptions to this rule of thumb. Even these animals, however, may masquerade as benthic invertebrates, often selecting ambush sites among the crinoids that they resemble. Most of the scorpionfishes exercise a sit-and-wait hunting strategy, although some species either passively or actively lure their prey. For example, algae grow on the heads and body surfaces of many scorpionfishes and may attract potential prey. At least one species has a dorsal fin that looks like a swimming fish as sinusoidal waves move down the fin.

Their food habits vary somewhat between species, but worms, cephalopods, crustaceans, and fishes are their primary prey. Some of the scorpionfishes lay gelatinous egg masses that float about the ocean until they hatch, at which time the larvae enter the plankton.