Syngnathidae

Big-belly seahorse

Hippocampus abdominalis

Males guarding eggs beneath the tail

• Black
• Brown
• Gray
• Temperate
• Globally widespread
• Marine fish
• Other
• Medium
• Temperate fish

Celebrated as the colossal heavyweight among all seahorses on Earth, the big-belly seahorse is a majestic, cold-adapted syngnathid endemic to the temperate waters of the southwestern Pacific. It is easily recognized by its enormous, rotund abdominal pouch that swells conspicuously in both sexes, creating an endearing bulbous pot-bellied profile. Coloration is richly variable, ranging from creamy-white, lemon-yellow, and orange to mottled dark brown, marked with scattered dark circular spots across the trunk and bold zebra-like banding on its elongated prehensile tail. A low, triangular coronet caps the head above a downward-curving tubular snout. Indigenous to southeastern Australia, Tasmania, and New Zealand, it frequents sheltered rocky reefs, giant kelp forests, sponge gardens, and jetty pilings down to one hundred and four meters depth. Using its strong prehensile tail to anchor against ocean swell, it vacuums mysid shrimps, amphipods, and microcrustaceans with rapid snout expansion. Males brood and nurture up to one thousand developing embryos in their pouch. Maximum total length attains thirty-five centimetres.

Sources: Australian Museum — Big-belly Seahorse, Hippocampus abdominalis