Well-wrapped feces allow lobsters to eat jellyfish stingers without injury

August 25, 2016

Lobsters eat jellyfish without harm from the venomous stingers due to a series of physical adaptations. Researchers from Hiroshima University examined lobster feces to discover that lobsters surround their servings of jellyfish in protective membranes that prevent the stingers from injecting their venom. The results are vial for aquaculture efforts to sustainably farm lobsters for diners around the world.

Lobsters grow for years before becoming a red-shelled main meal. In their early life stages, the larvae of slipper and spiny lobsters are nearly transparent and about the size of an adult's thumb nail. Lobster larvae ride around the ocean on the bodies of jellyfish while eating them alive, including the venomous portions of the tentacles.

Kaori Wakabayashi, Ph.D., is the leader of a research group at Hiroshima University and has studied lobster development with the goal of creating a food for farmed lobsters. Lobsters are not farmed on the scale of shrimp (prawns), crab, or fish because their development and nutritional needs remain poorly understood.

"Farmed marine species are often fed sardines, which has contributed to a dramatic decrease in global sardine populations. 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," said Wakabayashi.

Lobsters' intestines are lined with the same hard plates of chitin that cover the outside of their solid bodies. These plates probably defend the lobsters from jellyfish stings both on the surface and inside of their bodies. However, the intestinal armor does not cover the middle third of the length of the lobsters' intestines, leaving their midgut exposed to the stingers.

The stinging cells of Japanese sea nettles (Chrysaora pacifica) behave like extendable syringes, able to poke out and inject venom into the jellyfish's prey. The research team raised lobster larvae and jellyfish in the laboratory.

"Lobsters and jellyfish aren't common in research labs, so we have to find ways to adapt other tools. We have a very Do It Yourself mentality," says Wakabayashi.

The research team fed lobsters (Ibacus novemdentatus) a meal of only Japanese sea nettle tentacles and then suctioned up the lobsters' fresh feces. Under the microscope, researchers noticed the feces pellets were wrapped tightly in layers of a peritrophic membrane. These membranes usually allow certain small molecules to travel in both directions, but are apparently strong enough to prevent the stingers from reaching the lobster.

"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 another experiment, researchers confirmed that the lobsters are not immune to direct injections of jellyfish venom. When lobsters were injected with venom, researchers noticed that the lobsters' grooming behavior -- sweeping their bodies with specially adapted front legs -- was the last movement lobsters stopped making. Frequent grooming could be essential for lobsters' survival, possibly by preventing jellyfish mucus and the bacteria that comes with it from settling on the lobsters' bodies.
-end-
Find more Hiroshima University news on our Facebook page:http://www.facebook.com/HiroshimaUniversityResearch

Follow Assistant Professor Kaori Wakabayashi's research lab on Facebook by Liking her page: https://www.facebook.com/Aquatic-Invertebrates-Research-Group-in-Hiroshima-University-1663082570589779/

A Japanese language interview with Assistant Professor Kaori Wakabayashi is available at the following address: http://home.hiroshima-u.ac.jp/hiraku/younger_introduction/1_10/no-4/

Hiroshima University

Related Jellyfish Articles from Brightsurf:

Decaying jellyfish blooms can cause temporary changes to water column food webs
Decaying jellyfish blooms fuel the rapid growth of just a few specific strains of seawater bacteria, causing temporary changes to the water column food web.

Jellyfish with your chips?
Jellyfish could replace fish and chips on a new sustainable takeaway menu to help keep threatened species off the plate.

Jellyfish-inspired soft robots can outswim their natural counterparts
Engineering researchers have developed soft robots inspired by jellyfish that can outswim their real-life counterparts.

Jellyfish contain no calories, so why do they still attract predators?
New study shows that jellyfish are an important food source for many animals.

What makes a giant jellyfish's sting deadly
With summer on the way, and some beaches reopening after COVID-19 shutdowns, people will be taking to the ocean to cool off on a hot day.

Jellyfish help understand the timing of egg production
In animals, releasing eggs in a timely manner is vital to maximize the chances of successful fertilization.

Soft robot fingers gently grasp deep-sea jellyfish
Marine biologists have adopted ''soft robotic linguine fingers'' as tools to conduct their undersea research.

Stinging water mystery solved: Jellyfish can sting swimmers, prey with 'mucus grenades'
In warm coastal waters around the world, swimmers can often spot large groups of jellyfish pulsing on the seafloor.

How moon jellyfish get about
With their translucent bells, moon jellyfish (Aurelia aurita) move around the oceans in a very efficient way.

Jellyfish's 'superpowers' gained through cellular mechanism
Jellyfish are animals that possess the unique ability to regenerate body parts.

Read More: Jellyfish News and Jellyfish Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.