![]() The eyes are small and are situated at the base of its tentacles. There is a light purple shade on the spire of the shell, and a darker purple on the ventral side. The animal has a large head on a very flexible neck. The snail's shell is reverse countershaded, because of its upside-down position in the water column. Janthina janthina is a member of the family Janthinidae, snails that trap air bubbles with a layer of clear chitin to maintain their positions at the surface of the ocean where they are predatious on the hydrozoans. In addition to the bubble raft, only the veliger, or larval stage, has an operculum, and the shell is paper-thin to allow the animal to float upside down at the surface. They have been accompanied by smaller quantities of "Portuguese man o' war" Physalia physalisand the Violet Sea-snails which feed upon them (as seen above). Unusually warm waters and sustained winds has caused them to accumulate on the shorelines in quantities not seen in recent years. And I don’t even have to get wet."Violet Sea-snails" or Janthina janthina have accompanied the record numbers of "By-the-wind sailors" or Velella velella washing ashore on Bermuda's beaches. Whatever their size, violet shells on any beach give me a fine marine animal fix. On the same beach, I also found the biggest Portuguese man-of-war I’ve ever seen. The snails might be different species, or the big ones might have grown large due to these nutrient-rich waters. I’ve often found violet snail shells on Hawaii’s windward beaches, and could fit about 10 in my palm. When they mature, the tiny snails build their own bubble rafts and continue the nomadic existence. When the sperm hit their target, the female lays eggs and carries them with her beneath her bubble raft.Įggs hatch into a drifting underwater form. As a result, when a male violet snail senses a female in the area - they can’t see each other because violet snails have no eyes - he ejects sperm in her general direction. When an animal can’t control its course, it’s tough for the sexes to get together. Portuguese men-of-war are violet snails’ main food. Unlike us, violet snails don’t get a sting when they bump into blue bottle tentacles. That’s why during strong onshore winds, we find both species stranded on beaches. Throughout the world’s tropical oceans, violet snails and other members of their drifting community, including Portuguese men-of-war (called blue bottles here in Australia), are at the mercy of winds and currents. ![]() To lose the raft is to sink to the bottom and drown. In either case, the creature secretes mucus from its foot to coat its bubbles, creating a rubbery raft. Another theory is that the snail blows bubbles from air it has taken into its shell. Some believe that the snail agitates water with its foot to make bubbles. Healthy ones float offshore, upside down, on self-made bubble rafts. ![]() The exquisite shells, lavender above and purple below, lay 50 or so feet above the high tide line, suggesting that storm winds drove the snails toward shore and high waves spit them out. ![]() The long-dead animals I found stranded on this 2-mile-long sand beach, suitable for small plane landings, are the largest violet snail shells I’ve ever seen, nearly 2 inches long and an inch high. Sure, marine animals lying on beaches are dead or dying, but that means I can pick them up or turn them over and admire to my heart’s content. AIRCRAFT BEACH, EURIMBA NATIONAL PARK, Australia » For me, beach walking is often as rewarding as snorkeling. ![]()
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