Creature Feature: Look Who's Wearing Red Velvet This Season


Santa isn’t the only one sporting red velvet this season. The velvety red sponge (Ophlitaspongia pennata) also sports a bright red coat in December and all year long. This fiery-red sponge can also be found in colors ranging to a dull orange. (A color Santa never wears!)

This sponge is easily identified by its tell-tale sign of looking like vibrant red splashes on rocks. These splashes of red are usually small irregularly shaped patches that are very flat and thinly encrust the surrounding rocks. The thin crust is often only ¼ -inch thick. However, these encrusting patches can sometimes grow to three feet across.

The velvety red sponge is also commonly called the red encrusting sponge. An encrusting sponge is one that grows on something - like a rock - and covers it.

A common sponge, it can be found in the middle intertidal zone to the shallow subtidal zone from British Columbia south to Southern California. About ten different types of red encrusting sponges can also be found along the Pacific coast. The velvety red sponge prefers open coasts and areas shaded from sunlight. It can be found on darker, narrow crevices and on the undersides of overhanging rocks.

Just like its name implies (and Santa’s suit), this sponge is velvety and soft to the touch. It is, however, very tough. Tiny star-like pores are scattered across its surface.

Upon closer look at the red patches of sponge, you may find a tiny, adorable nudibranch called a crimson dorid (Rostanga pulchra). This little sea slug, with its matching vivid red coloring, is perfectly camouflaged on the sponge. It rarely leaves the sponge, since its red coloring would make it noticeable to predators. It feeds on the sponge leaving grooves that are its grazing path on the surface of the sponge. Even the nudibranchs red spiral egg case blends in with the sponge, making it hard to find.

If you want to find a velvety red sponge and an adorable crimson dorid, look for it in the low tide zone . Happy holidays.

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