Don’t try to crack this sea walnut. Otherwise known as comb jellies, these delicate marine animals drift through
the world’s oceans –- thriving everywhere from polar waters to tropical seas.
The coral-colored ridges on this comb jelly’s body are lined with tiny hairs called cilia. The hairs act like miniature propellers, powering the soft-bodied creature through the water as it collects food.
Unlike their notorious cousin, the jellyfish, comb jellies do not have tentacles with stinging cells. Instead, they have specialized sticky cells called colloblasts that snag plankton from the water.
Most comb jellies are transparent –- but as the exquisite variety pictured here shows, they are sometimes found in shades of red, pink, violet, or orange. What’s more, the invertebrates (which can be less than an inch to over a foot long) are usually bioluminescent, glowing with a light all their own.
Image copyright OAR/National Undersea Research Program (NURP), courtesy NOAA
