Marine Biodiversity - why does the sea have so much variety of life, yet so few species in comparison to the land?
Let’s focus on the Animal Kingdom for this…
From sponges and jelly fish to octopuses and whales the sea has a huge variety of animals.
Nevertheless, nowhere in the sea has the species richness of the rainforests.
Why?
1) What is Biodiversity?
Species, Genetic and Ecosystem diversity
Check out this 2 minute video for a quick explanation…
2) More Species are found on the Land than in the Sea
85% of species are found on land versus 15% in the sea.
Why? The land also has more ecosystem and niche diversity for species to evolve into.
Biodiversity In Water And On Land
Richard K. Grosberg, Geerat J. Vermeij, and Peter C. Wainwright
Published in Current Biology Vol 22 No 21
3) 27 out of 28 of the animal phyla, shown below, are found in the sea. Only 10/28 phyla are represented on the land
Faster diversification on land than sea helps explain global biodiversity patterns among habitats and animal phyla.
John J. Wiens
Published in Ecology letters 2015
These popular children’s stories demonstrate examples of typical sea and land animal phyla.
4 typical examples of animal phyla in the sea - Anenome (Cnidaria Phylum) Bristle Worm (Annelida Phylum) Periwinkle Shell (Mollusca Phylum) and Hermit Crab (Arthropoda Phylum)
2 typical examples of animal phyla on the land - Gruffalo and Mouse (Chordata Phylum) Butterfly (Arthropoda Phylum).
The arthropoda phylum is the most species rich phylum (mostly on land)
4) Why is the sea genetically more diverse than the land?
Life originated in the sea and radiated out to the lands. See the below fantastic short film that illustrates this. Most animal phyla evolved in the sea and only a few colonised the lands.
5) Where did life possibly begin?
Hydrothermal vents (the greatest Marine Biology discovery of the 20th Century)
The End
Join any Sea Kayaking Wales event to search out lots of examples of sea animal phyla…
Our BC Environment and Sustainability Guide module and Marine Biodiversity for Sea Kayakers courses focus a lot more on the ideas examined here.