Jellyfish drift through oceans worldwide. These creatures possess a simple biological structure, characterized by a gelatinous body and stinging tentacles. Despite their seemingly insubstantial nature and defensive capabilities, jellyfish are an integral part of the marine food web. This often leads to questions about which animals prey on such unique organisms.
Animals That Consume Jellyfish
A variety of marine animals include jellyfish in their diets, from large ocean dwellers to smaller invertebrates. Leatherback sea turtles are prominent predators, primarily eating jellyfish and other soft-bodied invertebrates. These large turtles can consume vast quantities, with some estimates suggesting they eat up to 73% of their body weight daily.
Ocean sunfish (Mola mola) are another significant consumer. These enormous bony fish largely subsist on jellyfish, including moon and comb jellies, making them a primary predator.
Several fish species also feed on jellyfish. These include the grey triggerfish, which uses strong mandibles to bite them, and generalist feeders like spiny dogfish, butterfish, swordfish, tuna, salmon, mackerel, and sardine.
Marine birds, such as fulmars, gulls, gannets, albatross, and penguins, opportunistically feed on jellyfish. Some, like thick-billed murres, even target jellyfish that aggregate smaller fish, using them to access concentrated prey.
Other invertebrates, including certain crab species like arrow and hermit crabs, scavenge on dying jellyfish or consume them when available. Sea anemones also prey on jellyfish that drift within their reach. Some jellyfish species are cannibalistic, preying on other jellyfish.
While less common, certain marine mammals, such as humpback whales and sea lions, occasionally consume jellyfish, though it is not a primary food source.
The Unique Challenge of Eating Jellyfish
Consuming jellyfish presents distinct challenges due to their stinging cells (nematocysts) and gelatinous composition. Predators like sea turtles have evolved adaptations to manage these defenses, such as thick skin around their beaks and papillae (backward-pointing spines) lining their mouths and throats that prevent prey from escaping and protect against stings. Ocean sunfish possess a slimy, viscous lining in their digestive tract, believed to protect them from stinging cells. Seabirds often peck at the inner tissues of jellyfish to avoid direct contact with tentacles.
Though composed of approximately 95% water, jellyfish provide valuable essential fatty acids, proteins, and micronutrients important for growth and reproduction. Animals often need to consume large quantities to meet their nutritional requirements.
The abundance and accessibility of jellyfish, particularly during large blooms, make them an attractive food source. Their slow movement and tendency to form dense aggregations mean predators can often expend less energy to capture a substantial meal. This combination of nutrients and ease of capture makes jellyfish a viable, and sometimes preferred, dietary component for specialized marine predators, even with their defensive capabilities.