Sea slugs: The British Columbian Doto
The Doto is a species of sea slug, also known as a nudibranch. It is a marine gastropod in the family Dotidae. This species was first discovered in British Columbia and has been reported as far south as Santa Barbara, California.
Another Northwest slug?
The Northwest is known for the slugs and snails that thrive in the undergrowth of its damp mossy forests. Critters like this also live under the sea, like Doto columbiana, commonly called the British Columbian Doto.
It’s a nudibranch
The British Columbian Doto belongs to a category of animals called nudibranchs (pronounced NEW-dih-bronks), often referred to as sea slugs. There are over 3,000 species of nudibranchs worldwide, but fewer than 20 species exist in the Puget Sound.
Classification of Doto columbiana
Excuse me? My “antennae” are called rhinophores!
The antenna-like structures on the nudibranchs’ heads are called rhinophores. These are a type of chemo-sensory structure, allowing nudibranchs to sense the world around them. The word “rhinophore” comes from the Greek word “rhino,” meaning nose, which is appropriate since they function as an organ of “smell.”
D. columbiana - profile of whole
preserved specimen stained pink
However, while humans smell scents in the air with their noses, nudibranchs “smell” or detect scents that are dissolved in the sea water around them to find food. The rhinophores’ worm-like appearance makes them an easy target for predators, so they can be quickly retracted into a trumpet-shaped rhinophore sheath for protection.
You are what you eat
D. columbiana on a colony of the hydroid Aglaophenia
Nudibranchs are carnivorous and get their pigmentation, or colors, from the food they eat. Nudibranchs that eat brightly colored creatures are brighter too. In fact, many have brilliant bodies of intensely contrasting colors.
The British Columbian Doto is quite drab by comparison. D. columbiana eats hydroids from the genus Aglaophenia. Hydroids are colonies of tinier critters called “polyps” that are related to jellyfish. An Aglaophenia colony looks like a brown fern frond or feather plume, and these neutral colors are incorporated into D. columbiana’s body to help camouflage it from predators.
D. columbiana conveniently lives on what it eats as well, laying its eggs on the underside of the hydroid’s branches. When the eggs hatch, the young larvae have shells which disappear as the nudibranchs become adults.
Taxonomy troubles
Doto columbiana has a soft body that does not preserve very well.
D. columbiana, like many soft-bodied critters, does not preserve well. The colors can be lost and the shape can become distorted. Benthic taxonomists, the scientists who identify these small marine critters, have to look closely at features like the cerata and rhinophores to determine which critter they have collected.
