Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient locomotion.
Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the “true jellyfish”) are exclusively marine, but some hydrozoans with a similar appearance live in freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. The medusae of most species are fast-growing, and mature within a few months then die soon after breeding, but the polyp stage, attached to the seabed, may be much more long-lived. Jellyfish have been in existence for at least 500 million years, and possibly 700 million years or more, making them the oldest multi-organ animal group.
Yes, turtles do eat jellyfish very frequently in the wild. In fact, jellyfish are the main food for the infamous leatherback sea turtle. Similar to turtles that live on land, sea turtles will eat anything they can get their mouth on, and jellyfish are one of the easier animals to catch in the ocean.
There are a few evolutionary adaptations that enable turtles to eat jellyfish without being stung. Their main defense mechanisms are:
- Thick skin, particularly around their beaks
- Papillae, lining their throats
- Armored shell
- Their ability to close their eyes when they attack
First, their beaks: Turtles, specifically Leatherbacks have very thick skin around their beaks. This allows them to chomp down without fear of stinging their mouth.
Additionally, their beaks are razor sharp. When they clamp down their lower and upper jaw, they can pierce almost anything. It is safe to say that soft-bodied organisms like jellyfish don’t stand a chance against the turtle’s jaws. In some cases, turtles can attack from the top, immediately separating the jellyfish from its venomous tentacles.
So what in the world is Papillae? As mentioned, an additional adaptation is the papillae which lines their throat to protect them from stings and also helps expel sea water.
Papillae are small spiny growths and provide an armor all the way from the esophagus down to the stomach. It is actually the exact same protein that makes up human fingernails and hair. The thick layer protects the turtle from any potential stings inside their throat or stomach.
The turtle’s shell: It is no secret that turtles have a hardened shell. Their shell protects their body from stings. Turtles do have a small number of nerve endings on their shells, but not enough to make a sting painful.
The blind attack: Their eyes are actually the most sensitive part of their body. A sting to the eyeball could be quite painful to a turtle. Luckily, they have learned to attack with their eyes shut. Protecting their eye sockets from any painful sting. If you ever watch a video of a turtle attacking a jellyfish, you will see it close their eyes right before the attack. This strategy greatly reduces their danger of being injured.