Sea Angel: Is it real?
Sea angels used to be known as a pteropod (small swimming sea slugs), but now are recognized as pelagic marine opisthobranch gastropod molluscs. Sea angels, also called cliones, live all over the world, both in polar and equatorial seas. Sea butterflies are similar to sea angels, but they also have a shell. Some sea angels even eat sea butterflies, which are slower and larger than themselves!
Sea angels are transparent, gelatinous, and unusually small (the average size is only an inch). Since sea angels are simultaneous hermaphrodites, their fertilization occurs internally and eggs are released to float with the ocean currents until they hatch on their own.
Although sea angels usually enjoy slow movement, as they only beat their winds once a second, they can also put on a burst of speed if they’re catching dinner.
If you have ever gone searching though tide-pools at the beach, you’ve probably seen your fair share of Mollusks. This is because mollusks live mainly in the sea (in the intertidal zone), although some live in freshwater.
Mussels, scallops snails, oysters (from which we get pearls!), and clams are only a few examples of types of mollusks. The mollusk body plan generally involves a muscular foot for locomotion, a body housing organs, a head with eyes or tentacles, and a mantle (which creates the shell). Usually, they absorb oxygen from the water using gills.
Only mollusks have a structure called a radula. Radulae (the plural of radula) are composed mostly of chitin, and can be as simple as a structure used to scrape algae off rocks, to the beaks of octopuses.