Jellyfish, recognized by their translucent, bell-shaped bodies and trailing tentacles, are common inhabitants of marine environments worldwide. These organisms, belonging to the phylum Cnidaria, are found across all oceans. Their tentacles are equipped with specialized stinging cells called cnidocytes, used for capturing prey and defense. While jellyfish are predators themselves, consuming plankton, fish larvae, and other small marine organisms, they also serve as a food source for various marine species. Understanding which animals prey on jellyfish provides insights into ocean food webs.
Sea Turtles: Specialized Jellyfish Eaters
Sea turtles, particularly the leatherback sea turtle (Dermochelys coriacea), are notable predators of jellyfish. Leatherbacks have evolved adaptations enabling them to efficiently consume these creatures. Their mouths and throats are lined with backward-pointing, spiny projections called papillae, which help them grasp slippery jellyfish and guide them down the esophagus. These papillae also prevent jellyfish from escaping once ingested.
Leatherback turtles can consume large quantities of jellyfish; during peak feeding seasons, they may eat up to 73% of their body weight daily, equating to thousands of calories from species like lion’s mane and moon jellies. Despite jellyfish being primarily water, their abundance makes them a viable food source, providing essential nutrients and hydration for these large reptiles. Other sea turtle species, such as loggerheads and green turtles, also include jellyfish in their diet, though not as exclusively as leatherbacks, often consuming them opportunistically.
Fish: Diverse Aquatic Predators
Many fish species incorporate jellyfish into their diets, showcasing various feeding strategies. The ocean sunfish (Mola mola) is a well-known example, with jellyfish and other gelatinous zooplankton forming a significant portion of its diet. These massive fish consume vast quantities to meet energy requirements, given the low caloric density of jellyfish. Their tough, leathery skin offers protection from stinging cells.
Other fish, like the grey triggerfish, include jellyfish when available, using strong jaws and teeth to tear them apart. Tuna and swordfish, fast-swimming pelagic predators, also consume jellyfish, especially when other prey are scarce, as they offer a quick energy source. Smaller fish, such as butterfish and juvenile species, associate with jellyfish, finding protection among their tentacles and sometimes feeding on parts of the jellyfish or smaller medusae.
Beyond Turtles and Fish: Other Marine Consumers
Beyond turtles and fish, other marine animals prey on jellyfish, highlighting their broad role in the marine food web. Marine invertebrates, such as sea slugs (nudibranchs), feed on jellyfish. Some nudibranchs, like Glaucus atlanticus, can consume stinging jellyfish and incorporate stinging cells into their own tissues for defense.
Some crustacean species, including crabs, feed on jellyfish. Crabs have been observed clinging to and consuming jellyfish, indicating this is a recognized feeding behavior.
Marine mammals like seals, such as sea lions, include jellyfish in their diet. While not a primary food source for all seals, it demonstrates their adaptability in foraging.
Marine birds, including Northern Fulmars and gulls, also prey on jellyfish, particularly those floating near the surface. Fulmars often selectively consume the more energy-rich parts of the jellyfish, such as gonadal tissue and oral arms, to maximize nutritional intake.