Secrets of 'smasher shrimp' property ladder revealed

October 28, 2020

Mantis shrimps carefully survey burrows before trying to evict rivals, new research shows.

Burrows in coral rubble are vital for the shrimps - providing a place to shelter, feed, moult, mate and lay eggs - and competition is fierce among both males and females.

Size matters to a homeless shrimp in search of a home, as burrows need to be big enough to fit into and small enough so they can block the entrance with their armoured tail.

Scientists from the University of Exeter and Duke University worked out the "ideal" burrow size and found that, when presented with empty burrows, shrimps chose a larger-than-ideal home - perhaps intending to grow into it.

However, when faced with occupied burrows, intruders fought hardest (measured by rate of success) for homes that were slightly smaller than ideal.

"We know that animals can assess a variety of factors, including the size of the opponent and the value of the prize, when deciding whether to fight and how hard to fight," said Dr Patrick Green, of the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall.

"In this case, as a smaller burrow is probably occupied by a smaller opponent, it seems mantis shrimps will compromise on the size of the home if it means an easier fight.

"It might be assumed that animals fight hardest for the biggest assets, but this study is an example of maximum effort being reserved for something that's 'just right'."

This species is one of a group of mantis shrimp called "smashers", as they strike with a club-like appendage that can kill prey and rivals, and can even crack aquarium tanks.

These strikes can accelerate as fast as a bullet, reach a speed of more than 50 miles per hour and create a flash of light by vapourising water upon contact.

When fighting rival shrimps, they generally take turns to throw one or more "punches" while the opponent curls up, using its tail as a shield.

Overall, resident mantis shrimps won most of the fights (69%) against intruders in the study.

However, when intruders fought over burrows slightly smaller than their ideal size, they won 67% of fights.

This victory rate dropped to just 13% for burrows that were much smaller or much larger than the intruder's ideal size, as calculated by the researchers.

When intruders did triumph, they usually did so by throwing the first punch and delivering more strikes.

The shrimps in the study were collected from their seagrass habitat off the Caribbean coast of Panama and kept in tanks for the experiment.
-end-
Funders of the research included the Human Frontiers Science Program and the National Science Foundation.

The paper, published in the journal Animal Behaviour, is entitled: "Quadratic resource value assessment during mantis shrimp (Stomatopoda) contests."

University of Exeter

Related Animals Articles from Brightsurf:

The sixth sense of animals
Continuously observing animals with motion sensors could improve earthquake prediction.

What it means when animals have beliefs
Humans are not the only ones who have beliefs; animals do too, although it is more difficult to prove them than with humans.

Taking a deep look into animals
Advances in neuroscience research and microscopy: a new technique makes it possible to clear a wide variety of different animals, making them transparent and allowing researchers to look deep into their organs and nervous systems.

Animals keep viruses in the sea in balance
A variety of sea animals can take up virus particles while filtering seawater for oxygen and food.

Plants and animals aren't so different when it comes to climate
A new study reveals that plants and animals are remarkably similar in their responses to changing environmental conditions across the globe, which may help explain how they are distributed today and how they will respond to climate change in the future.

Zoo improvements should benefit all animals
Zoo improvements should benefit all animals and include a wide range of 'enrichment' techniques, researchers say.

Even after death, animals are important in ecosystems
Animal carcasses play an important role in biodiversity and ecosystem functioning.

Through the eyes of animals
Humans are now closer to seeing through the eyes of animals, thanks to an innovative software framework developed by researchers from the University of Queensland and the University of Exeter.

Social influencers: What can we learn from animals?
Research from Oxford University calls us to reconsider how behaviors may spread through societies of wild animals, and how this might provide new insights into human social networks.

Animal embryos evolved before animals
A new study by an international team of researchers, led by scientists from the University of Bristol and Nanjing Institute of Geology and Palaeontology, has discovered that animal-like embryos evolved long before the first animals appear in the fossil record.

Read More: Animals News and Animals 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.