The hidden wonders of marine biodiversity

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.

Antarctic icefish

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 (Channichthyidae family). 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.

Deeper down, in the darkest depths of the ocean, finding a mate can be difficult, but deep sea male anglerfish (Ceratiidae family) have found a unique solution to this problem. Considerably smaller in size compared to the female, the male’s life depends on using his excellent sense of smell to find a female. Once he does find a female he fuses to her until nothing is left but his gonads which release sperm when the female’s hormones indicate she is ready to release her eggs.

This International Day for Biodiversity gives us a chance to discover our oceans. It also reminds us that marine environments are vulnerable and need to be taken care of. We may not be able to see all the life contained in the ocean but it still needs our attention and support.

Find out more about International Day for Biodiversity here.

Work area: 
Marine species
Go to top