Angels and Butterflies
Pteropods were among the first organisms to illustrate the devastation caused by the increasing acidity of the oceans (ocean acidification) due to the rise in carbon dioxide levels. Pteropods are planktonic sea snails. Some are tiny, at 0.5 mm, while others are just small, 10 mm or so. The largest is Clione limacina , subspecies Antarctica , which reaches 10 cm. It’s a predator that feeds on other, smaller pteropods. It uses microscopic hooks to grab its prey. The fully-shelled pteropod species belong to the Euthecosomes group, while the Pseudothecosmomata and Gymnosomata groups are partially shelled or have no shells. The shelled and partially shelled species are Sea Butterflies in the group Thecosomata, while the shell-less Gymnosomata are called Sea Angels. And yes, I capitalized those on porpoise (I did that on purpose, too). Systematic and taxonomic revisions are ongoing in these snails, and the number of species is unresolved. Among the Sea Butterf...