Marine biodiversity is the theme of this year’s International Day for Biodiversity - 22 May. Oceans cover about 70% of our planet’s surface area and there are an estimated 250,000 marine species.
Although about 40% of people live within 100km of the coast, there are many marine species that people have never heard of and most never see. Unique adaptations allow marine species to live in places that humans couldn’t, and while some of these adaptations are cool, some are just plain weird.
Living in the icy Southern ocean where the water is between -2°C and 4°C, there is a group of fish called Antarctic icefish (Channichthyidaefamily). Unlike our blood which is red, Antarctic ice fish blood is white. This is because their blood lacks haemoglobin, a protein that carries oxygen and is red. Because the water temperature in the Southern Ocean is so low, oxygen can dissolve into blood without needing haemoglobin. This is an advantage to the Antarctic icefish because it makes their blood more fluid and easier to pump around their bodies, which in turn, saves them energy in their cold home.
Between 600m and 800m below the ocean surface, where faint sunlight fades to blackness, the Barreleye fish (Macropinna microstoma) has ultra-sensitive eyes and a transparent head to help it find food. The Barreleye fish sits motionless in the water, looking up into the water above its head for prey that is silhouetted against the illuminated water above. When it spots food, the Barreleye fish swims vertically upwards, rotating its eyes to maintain visual contact with the prey. Its small mouth indicates that its vision is very accurate. Watch the video below produced by IUCN member, National Geographic, to learn more.
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