Zoology

Humboldt squid (Dosidicus gigas) can flash complex patterns of colour and light across their skin within milliseconds using chromatophores — pigment-filled sacs controlled by muscles. Research suggests these flashing patterns are a form of communication between individuals, potentially conveying information about prey, danger, or social status. Their skin also contains photoreceptors, meaning they may 'see' with their skin despite being colourblind in their eyes.

Octopuses have three hearts: two branchial hearts pump blood through the gills, while a third systemic heart circulates oxygenated blood to the body. Their blood is blue because it uses haemocyanin (copper-based) rather than haemoglobin (iron-based) to carry oxygen. Most remarkably, about two-thirds of their approximately 500 million neurons are located in their eight arms rather than their central brain, allowing each arm to act semi-independently.

Tardigrades ('water bears') are microscopic animals about 0.5 mm long that can survive conditions lethal to virtually all other life. They can endure temperatures from -272°C (near absolute zero) to +150°C, pressures six times deeper than the ocean's deepest trench, intense radiation, and even the vacuum of outer space. They achieve this by entering cryptobiosis — a state of almost zero metabolism — and by producing special proteins that form a glassy protective matrix around their cells.

While humans are pentadactyl (five digits), many successful mammalian groups, like even-toed ungulates, have reduced or adapted their digits to an even count for efficient locomotion and weight distribution.

These mammals, belonging to the order Artiodactyla, bear weight equally on two (or four) toes, unlike odd-toed ungulates (Perissodactyla) which bear weight on one or three toes.

These microscopic "water bears" can enter a state of suspended animation, shedding up to 97% of their water. This allows them to endure temperatures from -272°C to 150°C, intense pressure, and radiation doses 1,000 times higher than humans can withstand.