Behaviour

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.”

One of the common cuttlefish in the Marine Resources Center at the Marine Biological Laboratory
One of the common cuttlefish in the Marine Resources Center at the Marine Biological Laboratory

Cuttlefish smart enough to wait for better reward

Using a modified version of the Stanford marshmallow test, researchers at the Marine Biological Laboratory (The University of Chicago) discovered that cuttlefish had the ability to delay gratification for a better reward—and those that were able to do it for a longer duration possessed better cognitive learning abilities.

The findings, which demonstrated the link between self-control and intelligence, was published recently in the Proceedings of the Royal Society B journal.

Individual fish can be identified based on their behaviour and movements
Individual fish can be identified based on their behaviour and movements

Fish in study can be identified based on their movement and behaviour

This finding was based on research by a team of biologists and mathematicians from Swansea University and the University of Essex. It involved 15 three-spined stickleback fish observed individually in a fish tank containing two, three or five plants in fixed positions.

The Port Jackson (Heterodontus portusjacksoni) shark is a benthic, buccal pumping species that remain motionless for extended periods of time.

Do Sharks Sleep?

Sleep is ubiquitous across the animal kingdom but despite anecdotal reports of sleep-like behaviour in nurse sharks and other seafloor-dwelling species, the question of whether sharks actually sleep has been intensely debated but remains unknown. A key criterion for separating sleep from other quiescent states is an increased arousal threshold. True sleep is characterised by a lack of movement that can be rapidly reversed and a decreased awareness of surroundings.

The Fabulous Spawning Ritual of Striated Surgeonfish

Schooling striated surgeonfish

During a seven-year study of reef sharks in Tahiti, ethologist Ila France Porcher also observed the behaviours of various fish species. Here, she offers a detailed description and insights into the dynamic and mesmerising spawning events of the striated surgeonfish, which take place every year in the South Pacific.

Seeking Eye Contact: Fish Gaze Reveals Self-Awareness

For many years, I held a weekly feeding session for the resident reef sharks and their visitors in the study area where I observed their behaviour. If I had enough shark food, I would scatter crumbs into the water for the fish after the sharks had left. The fish knew this, so they had to wait, and while they were waiting, they were excited.