Jellyfish are marine invertebrates in the phylum Cnidaria, known for their gelatinous bodies and stinging cells (nematocysts). These specialized cells contain microscopic harpoons with toxins for prey capture and defense. Despite their stinging capabilities and being about 95% water, jellyfish serve as a food source for various marine animals.
Animals That Specialize in Eating Jellyfish
Some marine animals have developed adaptations to specialize in eating jellyfish. The ocean sunfish (Mola mola) is a key example, consuming large quantities. While once believed to subsist primarily on jellyfish, genetic analyses show they make up about 15% of their diet, alongside other zooplankton and small marine life. They must consume substantial amounts due to jellyfish’s low caloric content, supporting their large size and high growth rates.
Leatherback sea turtles (Dermochelys coriacea) are another specialist, with jellyfish forming a large, often exclusive, portion of their diet. They migrate to jellyfish-rich areas, consuming hundreds of pounds daily. Their unique digestive systems are adapted to process this soft-bodied prey. Certain tuna species, like bluefin and yellowfin, also include jellyfish in their diets, though less exclusively than leatherbacks.
Animals That Occasionally Eat Jellyfish
Beyond specialized predators, many animals opportunistically consume jellyfish as part of a varied diet. Various seabirds, including fulmars, gulls, and gannets, feed on jellyfish, especially those near the surface.
Crabs are also known to eat jellyfish, often scavenging on dying individuals. While not a primary food source, jellyfish provide protein and can be consumed when other prey is scarce. Certain fish species, such as butterfish and grey triggerfish, also include jellyfish in their diets.
Whale sharks, massive filter feeders, consume jellyfish, especially smaller ones, as part of their diverse planktonic intake. Even some baleen whales, like humpback whales, have been observed feeding on jellyfish in specific areas. Additionally, some jellyfish species are cannibalistic, preying on other jellyfish.
How Predators Manage to Eat Jellyfish
Predators of jellyfish have developed various mechanisms to cope with their stinging cells (nematocysts) and gelatinous composition. Leatherback sea turtles possess thick skin, providing protection from stings. Their mouths and throats are lined with backward-pointing papillae, which help them grip and swallow slippery jellyfish while preventing escape and minimizing sting exposure.
Ocean sunfish use beak-like mouth plates to suck jellyfish in and out, breaking them into manageable pieces. Their digestive tract may have a mucus lining for sting protection.
For large consumers like sunfish and leatherbacks, jellyfish’s low nutritional value (mostly water) is offset by sheer volume. Despite simple composition, jellyfish contain valuable fatty acids, with nutritional content increasing with size and stage, making them worthwhile prey.