Behaviour

Sand tiger sharks, top predators that live in coastal waters off the Eastern United States, have experienced drastic population declines over the past several decades. Understanding how these sharks move and interact could help biologists better conserve this species and determine how vulnerable they are to human activities. During summer, the sharks congregate in the shallow waters of Delaware Bay but are highly migratory, travelling as far south as the Carolinas and Florida during the winter and early spring.

After studying more than 23,000 sperm whale vocalisations recorded from 1978 to 2017 in the Pacific Ocean, researchers have concluded that sperm whales use distinctive vocalisations to identify themselves with specific whale clans.

Called “identity codas,” these vocalisations comprise sequences of clicking sounds that distinguish different social groups. They are different from non-identity vocalisations used across all the different whale clans.

Ocean eddies are coherent, rotating features which are ubiquitous at mid-latitudes and rotate clockwise In the Northern Hemisphere.

As these anticyclonic eddies move throughout the open ocean, a recent study suggests that the predators are also moving with them, foraging on the high deep-ocean biomass which tends to accumulate within.

Scientists have observed instances in which tuna rub themselves against the side of sharks. Apparently, they do this to dislodge painful parasites that cling to their head, eyes and gills.

“Shark skin is really smooth in one direction and it’s like sandpaper in the other,” said Chris Thompson, a Research Fellow at the University of Western Australia.

Researchers have discovered that male bottleneck dolphins form long-term social groups to help one another find mates and fight off competitors.

It was the first time such behaviour was observed in the animal world.

Their conclusions were based on data collected of 202 Indo-Pacific bottlenose dolphins between 2001 and 2006 in Shark Bay, Australia, using visual and auditory data. In the lab, the researchers then focused on studying the interactions of 121 of individuals for the next decade.

In general, the cephalopod’s sense of where its body is in space is quite poor, so this complex instinctive behavior may act to protect the arms from undetected predators nearby, which may mistake the tips of the octopus’s arms as fish or worms.

That octopus arms react to light has long been known. Its skin is covered in chromatophores, pigment-filled organs that change color when light falls upon them. They are behind the octopus’s color-changing camouflage ability.

Florida International University (FIU) marine scientist Yannis Papastamatiou, Ph.D. candidate Sarah Luongo, and a collaborative team of researchers wanted to uncover some of the mysteries of the white sharks (Carcharodon carcharias) that gather seasonally around Guadalupe Island, Mexico.