Canthigaster jactator, commonly known as ‘Hawaiian white-spotted toby‘ is a species of pufferfish belonging to the family Tetraodontidae. The genus name ‘Canthigaster‘ comes from the Greek ‘kanthos‘ meaning ‘spine‘ and ‘gaster‘ meaning ‘stomach‘ in reference to the ability of these fish to inflate their body as a defense mechanism. The epithet ‘jactator‘ comes from Latin and means ‘one who lunges or throws‘ possibly alluding to the sudden and rapid movements of this species. Canthigaster jactator is endemic to the waters of the Hawaiian archipelago, where it inhabits coral reefs and rocky areas at depths of 1 to 30 meters.
Canthigaster jactator is a small-sized fish that reaches a maximum length of approximately 10 to 12 centimeters. Its body is compact and somewhat oval, with a large head and prominent eyes. The skin is smooth, as it lacks scales, but has small erectile spines that are noticeable when the fish inflates as a defense mechanism. The body has a reddish brown background, fading to orange near the mouth and belly. It is dotted with crisp white speckles. The prominent eyes are green or turquoise. It lacks ventral fins, and the slightly wavy caudal fin is usually kept closed. The dorsal and anal fins are translucent and are both positioned far posterior. The upper pectoral fins are totally translucent. These features allow it to be differentiated from similar species, such as Canthigaster valentini, which has a more contrasting coloration with prominent black spots.
As for its diet, Canthigaster jactator is an opportunistic omnivore that feeds on a variety of small invertebrates, such as crustaceans, worms and molluscs, as well as algae and sponges. It is also known to consume soft and hard coral polyps, although this is less common. It uses its small mouth and beak-like fused teeth to bite and scrape food from reef surfaces. Its varied diet contributes to its ecological role as a controller of invertebrate and algal populations in coral reef ecosystems.
Reproduction of Canthigaster jactator is oviparous. During the breeding season, which generally occurs in the warmer months, males establish territories and court females through a series of visual displays. After courtship, the female deposits the eggs on a protected substrate, such as a crevice in the reef, and the male fertilizes them externally. The eggs are sticky and remain attached to the substrate until they hatch. The larvae, after hatching, are pelagic and develop in the water column before settling on the seafloor and metamorphosing into juveniles.
A curiosity of Canthigaster jactator is its ability to inflate when it feels threatened, ingesting water to increase its size and make it difficult for predators to swallow. In addition, like many pufferfish, Canthigaster jactator possesses tetrodotoxin, a potent neurotoxin found in its skin and internal organs, which provides an additional chemical defense against predators. Although this toxin is dangerous to many animals, it has also been studied for its potential in biomedical applications.
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