The smooth handfish (Sympterichthys unipennis) is officially no more, declared extinct by the International Union for the Conservation of Nature (IUCN). Although extinctions are now tragically common, this one is notable because it is the first marine fish species to be considered a “modern extinction”, that is with specimens collected in historical times rather than only being known from fossils. The declaration deals a blow to the theory the ocean is so vast marine fish will always find a new home. Worse still, several other handfish species are probably already gone.

Handfish live on the seafloor off the coast of Tasmania. They are like nothing else on Earth, having largely foregone swimming to pull themselves along the sea bed using flippers that look like hands. The Handfish Conservation Project sums them up with an anonymous quote: “If you've never seen a handfish before, imagine dipping a toad in some brightly colored paint, telling it a sad story and forcing it to wear gloves two sizes too big.” Museum specimens could easily be mistaken for discarded props from a Star Wars film.

Although they were probably never abundant, handfish were certainly diverse, with 14 species occupying different ecosystems when Europeans arrived in Australia. Sadly, however, most have not been seen in this century. The smooth handfish is known only from a specimen collected by French explorers in the early 1800s.

After two centuries without being seen, the ICUN has decided this one is almost certainly gone, changing its status to extinct. 

Dr Jemina Stuart-Smith of the University of Tasmania is an expert on handfish. She told IFLScience that, even though we know of no surviving populations of most other handfish species, marine biologists still hold onto hope, particularly for those that prefer deeper waters where divers seldom go.

The three species that do still exist are all rare, however, with two of them the focus of desperate conservation efforts. The red handfish is down to fewer than 100 adults, each of which has a personal webpage. To raise money to protect them, people and companies are paying to choose the name of an individual fish.

Handfish, in general, are threatened by increased sediments washed out of Tasmania’s damaged watershed. Climate change is almost certainly also a factor, and a scallop fishery that closed more than 50 years ago probably caused a sharp decline that pushed many species close to the edge.

Some handfish face specific threats. Stuart-Smith told IFLScience booming native sea urchins are eating the seaweed that helps protect the red handfish in their rocky habitats. Meanwhile, spotted handfish prefer sandy bottoms where the stalked ascidians they anchor their eggs to are being eaten by invasive sea stars.

The conservation project is appealing for divers to look out for the handfish of the surviving species and report any sightings. “We're collecting red handfish eggs from the wild to hatch in captivity where we can protect them from threats before releasing them,” Stuart-Smith told IFLScience.

The handfishes represent a warning about how extinction can creep up on us if an animal is not particularly large or famous. Handfish research was so under-resourced that until recently no one realized how endangered most of the species were.

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