Animals

Handfish

by Marcia Malory

Handfish (family Brachionichthyidae) are bony fish with pectoral fins that look like hands. They use these modified fins to walk on the bottom of the sea floor.

Although handfish may appear to be a "missing link", humans did not evolve directly from handfish, and human hands did not evolve from handfish fins.

Human beings are tetrapods - vertebrates that walk on land or that descended from other vertebrates that walked on land.

The limbs, hands, paws and claws of tetrapods evolved from the paired pectoral fins and paired pelvic fins of early lobe-finned fish. Handfish are not lobe-finned fish. They are ray-finned fish.

Both lobe-finned fish and handfish use their pectoral fins to walk along the bottoms of shallow bodies of water.

When two unrelated groups of animals develop similar body structures or behaviors because they live in similar environments, we say that this is an example of convergent evolution.

Handfish live off the eastern and southern coasts of Australia.

They belong to the order Lophiiformes (anglerfish).

Anglerfish get their name from the way that many species hunt for prey.

Part of an anglerfish's front dorsal fin (back fin) is modified to form a long filament that protrudes from its head. This filament is known as an illicium. There is often a fleshy growth, known as an esca, at the end of the illicium.

Many anglerfish use their esca as "bait" to lure other predator fish.

When an anglerfish wiggles its esca, another predator thinks it is a small fish and tries to eat it. When the other predator comes close to the esca, the anglerfish eats the other predator.

Handfish have short illiciums and it is not known whether they use them to lure predatory fish.

Handfish are small. They often have bright colors or eye-catching patterns.

In 2009, the Commonwealth Scientific and Industrial Research Organisation of Australia (CSIRO) identified nine new species of handfish. Only five species had been identified previously.

Changes to their habitat, such as those caused by fishing, pollution, changes in the temperature of the ocean, and the introduction of invasive species, have a strong effect on handfish populations.

The spotted handfish, which lives in the Derwent River estuary in Tasmania, is a critically endangered species.

It is about 6 inches long and eats small fish and small crustaceans.

The pink handfish, which is one of the newly identified species, was last seen in the wild in 1999. Only four specimens of pink handfish have ever been discovered.