Crustaceans

The two hermit crab species (Coenobita rugosus on the top left and C. perlatus on the top right), with the four shell types used in the research

Why two hermit crab species on same beach don't fight over shells

Researchers from the University of Bayreuth, Germany discovered how two hermit crab species co-exist on the same beach without fighting over limited resources like food or shelter.

The maze that the crabs in the study had to get through.

Study reveals crabs' spatial learning skills

Many studies about spatial learning in animals have focused on land animals, and less so in marine animals, possibly due to the difficulty in following them around.

This new study, led by Swansea University marine biologist Ed Pope and master’s student Ross Davies, gives a glimpse into the European shore crab’s level of spatial learning ability.

First, the team constructed a special maze that measured 75cm by 50cm. A single crushed mussel was placed at the end of it.

Some rockpool prawns prefer to stick with the food they found while others tend to forage for more choices.

Shy prawns fare better than bolder ones

Scientists at the University of Exeter studying rockpool prawns (Palaemon elegant) have discovered that they exhibit different personalities, and those that are "shy" tend to fare better when competing for food.

The findings of their study was published in Volume 140 of the journal Animal Behaviour.

In the study, the prawns, all taken from the Gyllyngvase beach in Falmouth, were tagged and tested on their level of boldness by placing them in an unfamiliar tank and observing how much they explored and ventured to the centre.

Invasion of the King Crabs

In many science fiction movies today—those with alien spaceships—the aliens look very similar to some of the underwater inhabitants of our own planet. Indeed, there is no need to invent some mythical creature to stir up the imagination of the viewer; it is enough just to show an image of a jellyfish, an octopus or a giant crab. And this story is all about the king crabs.

The fossil shrimp from Oklahoma and a recent shrimp
The fossil shrimp from Oklahoma and a recent shrimp

360 million-year-old shrimp

“The oldest known shrimp prior to this discovery came from Madagascar,” Feldmann said. “This one is way younger, having an age of ‘only’ 245 million years, making the shrimp from Oklahoma 125 million years older.”

The discovery is also one of the two oldest decapods (‘ten footed’) to which shrimp, crabs and lobsters belong. The other decapod, Palaeopalaemon newberryi, is of similar age and was found in Ohio and Iowa. “The shrimp from Oklahoma might, thus, be the oldest decapod on earth,” Feldmann explained.