Behaviour

Octopus at Curacao
Octopus on reef, Curacao

Octopuses’ arms can detect light

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.

There is evidence that white sharks form non-random social associations and may remain in proximity to each other to take advantage of pinniped kills.

Great white sharks have a secret social life

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. 

Sperm whale.  Photo by Eric Cheng
Will humans ever understand what these cetaceans are saying?

Will we learn to speak whale?

Project CETI is a nonprofit organisation applying machine learning and robotics to listen to and translate the communication of whales. The organisation is working to develop a deeper understanding of the complex system of communication that sperm whales use and share this understanding with the world.

Why do fish rub themselves against a shark?

Fish rubbing themselves against a shark's body may sound as if they have a death wish, but this is precisely what some fish have been spotted doing. And it turns out that such behaviour is more widespread and frequent than one would think.

A study led by the University of Miami (UM) Shark Research and Conservation Program at the Rosenstiel School of Marine and Atmospheric Science uncovered over 40 instances of fish rubbing themselves against a shark’s skin in over ten locations around the globe.

While chafing has been well documented between fish and inanimate objects, such as sand or rocky substrate, this shark-chaffing phenomenon appears to be the only scenario in nature where prey actively seek out and rub up against a predator.

Surfers are the highest-risk group for fatal shark bites, especially by juvenile white sharks
Surfers are the highest-risk group for fatal shark bites, especially by juvenile white sharks

"Mistaken identity theory" behind shark bites put to the test

Why sharks sometimes bite humans remains unclear, but potential reasons include mistaken identity, whereby sharks are thought to mistake humans for their typical prey; curiosity; hunger; and defensive/offensive aggression.

The mistaken identity theory has received little scientific scrutiny and the visual similarity between humans and pinnipeds at the surface has been debated largely on the basis of human visual perception, rather than that of sharks.

Whale watching off Iceland
Whale watching off Iceland

Do Tourist Boats Stress Out Whales?

Do whale watchers bother whales? A number of studies on tourism's impact on whales, which were based on behavioural observations, have concluded that tourism caused only minor disruptions to the mammals. 

For example, in 2015, a study led by Marianne H. Rasmussen, director of the University of Iceland Húsavík Research Centre, found that whale watching as currently practised does not seem to be having any long-term negative effects on the life expectancy of minke whales.

Chromis viridis (green chromis) is a species of damselfish.

Fish trust friends in a crisis

In social animals living in the wild, individuals rely on their buddies to alert them if a predator is lurking.



All animals aim to balance the risk of predation against the energy investment necessary to execute an escape, to maximise the number of correct reactions (e.g. reacting to the presence of a predator) and minimise reactions to inaccurate information (e.g. reacting to harmless stimuli).

Trust among individuals is critical. This is true for humans as well as many other species, including fishes.

Study co-author Jacob Johansen, Ph.D.

Sharing resources in a civilised manner? Sharks at Tiger Beach don't get into a food fight but appear to wait patiently in line for their turn.

Shark species takes turns hunting

Niche partitioning of time, space or resources is considered the key to allowing the coexistence of competitor species, and particularly guilds of predators such as sharks.

However, the extent to which these processes occur in marine systems is poorly understood due to the difficulty in studying fine-scale movements and activity patterns in mobile underwater species.

Pixabay / Public Domain
Pixabay / Public Domain

Why marine creatures swim in circles

Thanks for advancements in tracking technologies, scientists have discovered an intriguing behavioural trait amongst some marine species: They sometimes swim in circles.

When studying the navigational abilities of sea turtles, Tomoko Narazaki, a marine researcher at the University of Tokyo, observed that the turtles in her study would swim in circles so constantly “just like a machine.”