[Here is an article I wrote for the Richmond River Historical Society Bulletin. I write a regular, short column, ‘What’s in the Nature Room?’, about an object in that room. Thanks to the Queensland Museum for IDs of the specimens.]
If you’re snorkelling in the seagrass beds or fishing in the lower reaches of the Richmond River, you might be lucky enough to see pipefish and seahorses. They hide there among the seagrass, sucking in plankton and the tiny animals that live on the leaves.
The seahorse has a prehensile tail, wrapping it around a seagrass leaf to steady itself and hide. Pipefish tails are not so agile, but the animals are camouflaged by being about the same shape and width as the seagrass leaves, and drifting gently about among them.
Some pipefish species have the shortest life spans known for vertebrates and can reproduce as early as two weeks after being born – they grow fast (up to 2 mm a day) and die young (some at about 5 months).
The females of both pipefish and seahorses transfer their fertilised eggs to the males, who incubate them in a pouch or just in a group along the underside of the trunk or tail, depending on the species. This is handy for protecting the young, unlike, say, octopuses, which lay their eggs under a rock or in a crevice and must be constantly on hand to protect them from predators. Young pipefish, after birth, move away from the father and are completely independent. Predators they must avoid include turtles, seabirds and fish.
The two pipefish with the shorter ‘snouts’ in the photo are labelled Lissocampus runa (the javelin pipefish). This pipefish occurs in shallow sheltered inshore areas and tidepools to 3 metres depth, from Hervey Bay, Qld, to south of Nowra, NSW.
The third, with the longer snout, is a Duncker’s pipehorse (Solegnathus dunckeri). Its range extends from Fraser island, Qld, into the southern NSW coast. It reaches a maximum of 50 cm. Duncker’s pipehorses are usually found at depths of 20−80 metres, but are occasionally washed ahore on ocean beaches.
The seahorse is likely to be White’s seahorse (Hippocampus whitei), which is known from Mackay, Qld, to just south of Sydney, NSW. It reaches about 17 cm in length.
Unfortunately, seagrass meadows are one of the most threatened ecosystems on Earth, because of human pollution and damage to the leaves, stems and roots by boat propellers, trawlers’ nets, and dredging. This endangers larger creatures like dugongs, which eat seagrass, too.
All species of seahorses and pipefish are protected by law, so look but don’t touch!