The Riches Of The Seas - Chapter 8

Source: Food and Agriculture Organization of the United Nations, 2013, Caroline Hattam, Plymouth Marine Laboratory,   "The Youth Guide to Biodiversity" 1st Edition (Chapter 8) Youth and United Nations Global Alliance. Reproduced with permission.

Chapter 8. Verbatim.

Galápapos crab.

© Reuben Sessa

Did you know that life began in the ocean some 3.5 billion years ago? And did you know that scientists estimate that there may be up to 10 million species living within the seas? 

The marine environment is home to a stunning variety of beautiful creatures, ranging from single-celled organisms to the biggest animal ever to have lived on the Earth – the blue whale. 

This chapter describes the multitude of life found in the seas, the uses we make of it and how marine life is changing because of this use and because of global environmental change.

Marine Life

We know much less about marine biodiversity than we do about terrestrial biodiversity, but we do know a few interesting facts:

 •• There are 35 animal phyla (groups of animals such as arthropods and molluscs) found in the seas, 14 of which are only found in the sea.

•• The marine environment is home to both the largest mammal on the Earth (the blue whale) and the biggest invertebrate (the colossal squid).

•• The largest marine mammals are often dependent on the smallest marine life for food. For example, blue whales feed on krill. Krill are small animals that weigh about one gram each, and a blue whale needs to eat about 3.6 million of them every day!

•• The fastest animal in the sea is the sailfish which can reach speeds of 100 km/h (imagine someone swimming at the same speed as your car the next time you are on the highway).