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Breeding Tank Busters in the Wet Lab

Marine biology undergrads rearing reef creatures in the RWU Wet Lab provide a primer on the predatory mantis shrimp
Of the hundreds of species of mantis shrimp living in oceans around the world, the peacock mantis shrimp — a native of the Indo-Pacific region — boasts some of the most brilliant array of coloring of its shell. Davis and Rezendes are working with a local species found in Mount Hope Bay and Narragansett Bay.

Editor's note: This story is part of the 10 on Tuesday series, which provides a fresh take on interesting university initiatives, research projects, campus happenings and more.

BRISTOL, R.I. – In the depths of the Marine and Natural Sciences building, far beneath the buzzing lecture halls, junior Avery Davis and senior Ryan Rezendes spend hours at a time observing a series of clear plastic containers, monitoring water flow and temperature, and keeping close watch on the unsuspectingly lethal crustaceans within – the mantis shrimp.

Since September 2012, Davis and Rezendes have studied the mantis shrimp species in the RWU Wet Lab. Initially interested in the stomatopods’ diet – the pair conducted analyses of the creatures’ stomach contents to determine major prey – the project shifted in scope when they discovered that one of the mantis shrimp had laid eggs. With the resources of the Wet Lab at their disposal – as well as supervision from seasoned experts and RWU faculty Dale Leavitt and Andrew Rhyne – Davis and Rezendes have since attempted to develop aquaculture techniques for the mantis shrimp.

While researchers have previously investigated rearing mantis shrimp in labs, those projects have relied on harvesting the mantis shrimp from the wild. To their knowledge, Davis and Rezendes’s project is the first attempt to breed the crustaceans in captivity:

“We looked at other scientific papers that have been written on raising mantis shrimp, but none of them have ever laid eggs in captivity and then taken those eggs and raised them,” Davis says.

Among their findings, Davis and Rezendes discovered that water temperature stimulated the production of egg. The water in the Wet Lab is approximately four degrees warmer than the Mount Hope Bay, where the mantis shrimp were originally collected, which triggered their response to spawn and lay eggs.

From the dangers of handling mantis shrimp to the challenges of breeding them, here are 10 tidbits about mantis shrimp:

  • Mantis shrimp eggs are covered with a clear mucous layer (depicted at right in Davis's photo of one of the females carrying eggs in the Wet Lab)  that has to be carefully removed with tweezers. They are then placed in a water flow system that keeps them moving. “Basically, we’re providing aeration to the eggs artificially as opposed to the mother,” Rezendes says.
  • The water flow system also keeps the larvae separated from the adults to reduce the risk of cannibalism. Females will eat their eggs if they have not received enough aeration.
  • When the eggs are laid, the female steers them into a sack that resembles bright orange cotton. She then begins a process of rolling and unrolling the sack to stimulate growth.
  • Determining the sex of the mantis shrimp is difficult – it has to be done manually by turning them over to locate their sex organs. To avoid any potential dangers, Davis and Rezendes have been, “putting them in solitary and seeing if they have any eggs.” The females do, the males don’t.
  • Mantis shrimp look like a cross between a shrimp, lobster and praying mantis – hence the name. The upper half of the body looks like a praying mantis and shrimp, and the tail resembles a lobster’s. Despite their name, mantis shrimp are actually related to lobsters – not shrimp.
  • Though there are hundreds of species of mantis shrimp, they are generally classified into two groups: smashers and spearers. Smashers have developed a club that they use to bludgeon and break open their prey. Spearers have spiny appendages with barbed tips. The speared mantis shrimp are found locally in the Mount Hope Bay.
  • Mantis shrimp are stealth predators and masters of hide-and-seek. It waits for a small creature to pass by before darting out to impale the prey with its spear and then retreats into its lair to enjoy lunch. “They have the quickest strike in the animal kingdom,” according to Davis.
  • A complex visual system makes vision the mantis shrimp’s number one sense, Rezendes says. While humans have just three primary colors, mantis shrimp have 16 to 18 – they can see an estimated 10,000 colors and can also see infrared.
  • Mantis shrimp enjoy popularity in the Asian food market and (despite their destructive nature) are renowned for their sweetness.
  • Also known as “thumb splitters,” and “tank busters,” mantis shrimp are tremendously destructive. They can cut through a single pair of gloves (fishermen are known to wear up to three pair to avoid cuts) and their strike force is that of a .22 caliber pistol – enough to crack a glass aquarium. 

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