Do you really know animal phyla? Quiz

Answer: Tardigrades

The 800 species live in marine sands and temporary water films on plants. When the water films dry out, these animals lose water and shrink. They become dormant and survive extreme temperatures for at least a decade. Seems like the creatures you want to send on interplanetary missions!

Answer: Nematomorpha

Nematomorpha are also called horsehair worms. Many parasitic creatures can alter the behaviour of their hosts to help themselves. The adult worm has to be in water to survive and that's why it causes the insect to jump into the water.

Answer: Nemerteans

Nemerteans are called ribbon worms. There are ~1,000 species and they have a body cavity called a rhynchocoel. They range in size from 20 cm to 20 meters long! Beware as the proboscis may have stylets that discharge a paralytic toxin. But you'd be in danger only if you are immobile on the ocean floor.

Answer: Onycophorans

Onycophorans are called velvet worms. They may resemble the ancestor of arthropods. Arthropods have jointed legs. The 150 species live in leaf litter in tropical environments.

Answer: Placozoan

The single identified species is Trichoplax adhaerans. It does not have any organs or internal structure. It feeds by absorbing food (mainly microbes) through the surface stuck to the aquarium.

Answer: Acoela

Although morphologcally acoel flatworms resemble Platyhelminthes flatworms which do not have a coelom (body cavity), DNA analysis shows that they are not related. The 400 species are found in sandy or silty sediments and also among algae.

Answer: Loricifera

Priapulids, Kinorhyncs and Loriciferans are benthic marine ecdysozoans. Lorica means a corset in Latin. These tiny (only several hundred micrometers long) have a body divided into five regions. Surrounding the body is a corset made of six cuticular plates.

They can "telescope" their mouth, head and neck out of the corset. The larval or juvenile form is very different from the adult.

Answer: Bryozoa

The 4,500 species of Bryozoans are colonial animals. Their "house" is secreted by the external body wall. Each member of the colony is only 1-3 mm long. A single animal divides asexually to form the colony. But a single colony may contain 2 million members! The stiff tissue that connects the members can create beautiful patterns.

They can make reefs in shallow waters. Most are marine, but a few live in fresh water. Bryo means moss and zoan means animal.

Answer: Chaetognata

Chaetognaths ("bristle-jaw") are transparent and shaped like an arrow. They are predators which eat small invertebrates such as copepods. They are found in polar oceans as well as warm waters. They are found both on the surface and deep ocean.

Answer: Xenoturbellida

These strange animals are described as being nothing but "drifting digestive systems". They do not have any defined organs and even the gut is incomplete. Bock was a Swedish zoologist (1884-1946). He discovered the first species Xenoturbella bocki in 1915. The first published description was by Weinar Westblad in 1949.