Shortspine Porcupinefish

The black-blotched porcupinefish (Diodon liturosus), commonly referred to as the shortspine porcupinefish, belongs to the family Diodontidae. This species primarily inhabits the tropical and subtropical regions of the Indo-Pacific, where it resides in coral and rocky reefs, as well as inshore waters. It is also known by other names, such as the blotched porcupinefish and the brown-backed porcupinefish.

The black-blotched porcupinefish is a medium-sized marine species, reaching lengths of up to 65 centimeters (26 inches), with an average observed size of approximately 45 centimeters (18 inches). Its distinct morphology includes an elongated body, a spherical head, prominent round eyes, and a large, typically ajar mouth. The fish is characterized by substantial pectoral fins, the absence of pelvic fins, and its anal and dorsal fins positioned near the caudal peduncle, which move in unison during swimming. The fins exhibit a uniform shade of white or yellowish, devoid of any spotting.

The fish's epidermis is smooth and firm, while its spines, formed from modified scales, are oriented towards the posterior. Its coloration varies from light brown to sandy-yellow, with distinct dark blotches encircled by white, and a pale ventral side. It can be mistaken for the long-spine porcupinefish (Diodon holocanthus), but it is distinguishable by its shorter spines and the absence of a dark streak between the eyes.

In response to potential threats, the porcupinefish can inflate its body by ingesting water, thereby deterring predators with its increased size, while simultaneously erecting its spines defensively. Additionally, certain body parts—including the liver, skin, gonads, and viscera—contain tetrodotoxin, a potent neurotoxin that serves as an effective deterrent against predation.

Geographically, the black-blotched porcupinefish is distributed throughout the Indo-Pacific, from the eastern coasts of Africa to 🇯🇵 Japan, the Society Islands (🇵🇫 French Polynesia), and Western Australia, as well as the southeast Atlantic Ocean along the 🇿🇦 South African coast. Adult porcupinefish prefer lagoons, reef tops, and seaward coral or rocky reefs, typically inhabiting depths ranging from 1 to 90 meters, with a preference for areas between 15 and 30 meters.

Dietarily, the porcupinefish primarily consumes sea urchins, gastropods, and crustaceans. It leads a predominantly solitary existence, except during mating periods. The species exhibits nocturnal behavior, with peak activity occurring at dusk and dawn. During daylight hours, it is commonly found sheltering within caves or beneath ledges.