Story: Marine animals without backbones
Page 7 – Lancelets, lampreys and hagfish
Lancelets belong to a subgroup of vertebrates. Technically, they are invertebrates because they lack bony structures; however, their bodies are supported by a gelatinous rod of tissue – a precursor to a backbone.
Lancelets, or puhi (Epigonichthys hectori) are small, transparent animals that spend most of their life partially buried in sandy burrows just below the low-tide zone. They filter-feed, using the whiskery growths around their mouths to trap food. New Zealand has just one species.
Lampreys are slime-covered animals that resemble eels but lack bones. And like eels, they spend part of their lives in rivers and part in the sea. For their first four years lampreys are blind filter-feeders, then they develop eyes and migrate to sea. It is not established how long they remain there, but during this time they become blood suckers, preying on large fish and marine mammals. Lampreys attach their circular sucker mouths to their host’s body, rasping away the flesh and sucking at the tissues. They return to freshwater rivers to spawn before dying. The adult form of New Zealand’s sole species, Geotria australis, was a favoured food of inland Māori.
Whanganui Māori used an extensive system of weirs to trap lampreys, or piharau, as the creatures made their way upriver in winter to spawn. The projections of mānuka stakes were built from the riverbank towards the middle of the river, directing the lampreys into a net trap. Māori in Southland used to catch lampreys by hand on rock walls as they ascended the Mataura Falls.
New Zealand has three species of hagfish, an entirely marine group. Hagfish are generally scavengers of dead fish and marine-mammal corpses, although they will attack living fish, worms and crabs. They exude copious quantities of blue slime from their skin if disturbed, which is why they are also known as snot eels. For some people the common coastal hagfish, or tūere (Eptatretus cirrhatus), is good eating, once the slime is removed. At nearly 1 metre in length, it is one of the larger hagfish known.