Jellyfish stingers are formidable things, used both as defenses against predators and to capture the invertebrates' own prey. Scientists have observed lobster larvae feeding on the jellyfish tentacles and stingers, too. So how are the baby crustaceans able to survive ingesting these deadly stingers? The answer lies in a weird way they package their poop.
Before they reach maturity, lobster phyllosoma — the name for the piny, lipper and coral lobter larvae before they reach a juvenile state — are tiny things only a few centimeters long. To survive, they float in the ocean and attach themselves to passing jellyfish, then eat the jellyfish alive, tentacles, stingers and all, while catching an underwater ride to part unknown. But those stingers are poisonous, right? According to a new study in the journal Plankton and Benthos Research, the lobster larvae can handle eating the syringe-like stingers by creating a protective membrane around what they eat. This membrane prevents the tiny stingers from injecting the lobsters with venom while inside their digestive tract.
A Hiroshima University research group headed by Dr. Kaori Wakabayashi fed the larval smooth fan lobsters (Ibacus novemdentatus) an exclusive diet of sea nettle jellyfish (Chrysaora pacifica) tentacles. To examine what happened inside the lobsters' digestive tract, the scientists suctioned up the freshly excreted lobster feces — careers in science! — and found the fecal pellets wrapped in a membrane created before the digested food reached the middle of the intestines. This membrane is peritrophic and semipermeable, which means it allows certain nutrient molecule to pass through while blocking other things (like stingers).
"Based on the contents of their feces, we think that the lobster larvae only digest fluid-type foods, which is vital to know as we develop an artificial food for farmed lobsters to grow efficiently and healthily," said Wakabayashi in a press release announcing the findings.
In a separate experiment, Wakabayashi and her team determined that it is indeed this membrane protecting the lobster by proving the lobsters aren't immune to the jellyfish venom — nine out of 10 crustaceans died when the venom was injected directly into their flesh.
Beyond just discovering cool facts about sea creatures, this new research could have implications for the cultivation of new food sources. Farmers are able to feed large populations of crab, shrimp and fish, because we understand how they eat. Lobsters, however, generally have to be caught in the wild, as farming them has proved tricky due to how little we understand how they feed. If scientists can learn more about how the crustaceans sustain themselves, we could farm lobsters more easily. In fact, the goal of Wakabayashi's team is to develop an artificial lobster food for more sustainable aquaculture.
"Farmed marine species are often fed sardines, which has contributed to a dramatic decrease in global sardine populations," said Wakabayashi. "In the future, artificial food will empower farmers to provide their lobsters with convenient, sustainable, and safe nutrition regardless of weather, locality, or the availability of other marine resources. Knowing what the lobsters ate also ensures greater food safety for people."