Strange marine creatures abound

Abstract

A number of fishermen, divers and members of the public have over the past few weeks contacted the Spot the Jellyfish team to report the presence of strange creatures in the seas, besides the current, well-documented mauve stinger (Pelagia noctiluca) jellyfish bloom. These unfamiliar marine creatures are actually not jellyfish but comb jellies (or ctenophores) and pelagic sea squirts (such as salps and pyrosomes). The latter are more complex than jellyfish as they even have a nerve cord. Comb jellies and sea squirts are not dangerous to humans since, contrary to jellyfish, they lack stinging tentacles. Instead they have sticky tentacles to capture their prey, or they filter plankton out of water through a siphon. Comb jellies owe their name to the numerous rows, or combs, of small hairs known as cilia, by which they propel themselves. Normally, they bloom during the summer season, and their unseasonal blooming this year may be another symptom of the increasing warming of the Mediterranean Sea.