Without the blue/purple rhinophores, it would be hard to know which end is the front and which is the back
Nudibranchs are known for their wild colors and patterns, and this nudibranch is no exception. The purple-crowned sea goddess is the smallest nudibranchs I am writing about this month. This tiny nudibranch will only grow to an inch max. Although this is tiny, the smallest adult nudibranch length is only 0.16 inches. Interestingly, despite most nudibranchs being small, there is a nudibranch that grows to over 20 inches long!
Without the blue/purple rhinophores (sensory organs that look like horns), it would be hard to know which end is the front and which is the back. If you look closely, you will see the head is on the right. The body has a white stripe running down the back with a chessboard white and black pattern along the back. The trim of the mantle is a distinct orange.
These creatures are considered an uncommon sighting, although I have been lucky to have seen several. Like other nudibranchs, these creatures stay on the bottom. Purple-crowned nudibranchs typically live on or near shallow reefs, to a maximum depth of around 75 feet. The nudibranch in this photo was found in a similar environment, a shallow Florida Keys reef.
If you look closely, you will notice something is missing from this nudibranch, the anal gills, which are how nudibranchs breathe. For the purple-crowned sea goddess, this small decorative plume is usually on the back opposite the rhinophores. Did you know some nudibranchs can retract their anal gills into a pocket inside their body? Nudibranchs that can do this are referred to as “cryptobranchs”.
You might be wondering how these creatures protect themselves from predation, as they do not appear to have a defense mechanism. Indeed, they did lose their protective shells through their evolution. In place of their shell, nudibranchs have developed some amazing defenses. Aside from camouflage, they are able to consume the stinging cells of sponges and hydroids and use them in their own defense. The ingested nematocysts (stinging cells) do not hurt the nudibranch amazingly. Nudibranchs also use aposematism, which is using their bright body colors as a warning to would be predators that they are not worth eating.
Nudibranchs lost their protective shells through their evolution
Did you know?
- Not all nudibranch live on the bottom. Neustonic Glaucus as well as Cephalopyge trematoides and Phylliroe bucephalum live within the water column and not on the bottom.
- Nudibranchs have external bilateral symmetry, but not internal bilateral symmetry.
- Purple-crowned sea goddess feed on sponges.
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