The giant carnivorous amoeboid

A giant among unicellular organisms that builds its own shell and resembles a carnivorous sponge has been listed in the Top 10 Species for 2014.

Spiculosiphon oceana, discovered 30 miles off the southeast coast of Spain, is a single-celled foraminifer 4-5cm high. The Foraminifera are a group of amoeboids that are able to create a shell for protection, and this new variety is the largest known specimen in the Mediterranean. The species name, ‘oceana’ was given in honour of the non-profit organisation that collected the first samples.

The unusual appearance of this new species originally led researchers to mistake it for a multicellular carnivorous sponge. Its shell is composed exclusively of skeletal pieces of dead sponge known as spicules, collected from the seabed and glued together with a ‘protein glue’ similar to that used by sponges. It also feeds like a carnivorous sponge, extending pseudopods (a protist’s version of arms) outside its shell to feed on invertebrates that get trapped in the spiny structures.

This foraminifer belongs to a family of organisms known as schizaminids, of which only 11 species are known. S oceana is the second species of the Spiculosiphon genus and the only one in the Mediterranean. The only other species in this genus, S radiata, which was discovered in Norway at depth of 100m, is half the size of its Spanish relative.

The Top 10 Species list is compiled annually by an international committee of taxonomists and other experts from among the roughly 18,000 new species named during the previous year. It is published on May 22 to coincide with the birth date (May 23) of the Swedish botanist Carolus Linnaeus, who is considered the father of modern taxonomy.

The list also includes three other tiny newcomers to science: a miniscule skeleton shrimp from Santa Catalina Island in California, a clean room microbe that could be a hazard during space travel, and a teensy fringed fairyfly named Tinkerbell.

Also on the list are a gecko that fades into the background in its native Australia and a fungus that, conversely, blazed its way into contention by virtue of the bright orange color it displays when it’s produced in colonies. Crawling slowly into the final spot on the alphabetical list is Zospeum tholussum, a tiny, translucent Croatian snail from one of the world’s deepest cave systems.