Marine biodiversity

marine biodiversity or how weird the sea is

By Dr J Floor Anthoni (2001)

One of the biggest mistakes is to treat the sea as if it were an extension of the land. We tend to apply the same scientific principles and the same ecological laws, without realising that the marine environment is too strange for these laws to apply. Please read this chapter with care, and also the related pages, because it gives you a new understanding of how the sea works and why a century of ocean management has not delivered the expected results. Also take the challenge to read about our most recent marine discoveries with the DDA method.

marine biodiversity The sea is a totally different place. How does it differ from the land? How many phyla and species? How does it affect marine reserves? How can marine reserves fail? Why has ocean management failed world-wide?
related pages
on this web site
Conservation principles: understanding conservation of the environment and how it can fail (30p)
Resource management: important knowledge for understanding biodiversity and conservation (30p)
Marine conservation: how to save the sea, and why so many ideas are not working. (34p)
Global threats to humans, atmosphere, land and sea. (20 p)
Marine habitats: an introduction to the life-determining factors in the sea. (16 p)
The intertidal rocky shore: principles of the rocky shore zoning, and an identification of shore species. (80p)
Myths and fallacies in marine conservation, marine reserves, MPAs and marine science. (large)
the war for marine reserves in New Zealand: why marine reserves can't work where degradation reigns. (large)
Biorealms of the planet: the major biospheres and their differences. (4 p)
Red Data Book of NZ: a summary of the list of endangered species in New Zealand. (9 p)
Marine degradation: how the seas degrade, why, and how this works (25p)
Decay: images of degrading marine habitats, and an explanation how degradation works (large)
DDA: our epoch-making discoveries with the DDA method show that the sea does not work as thought (large)
Sitemap: discover the gems in the Seafriends web site from our complete site map (11p)
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Marine biodiversity and differences between land and sea

The sea is such a different place to live, that it is perhaps not possible to imagine how different, not even after years of diving and observing underwater life. Living in water is profoundly different from that on land. Take some time to read carefully what follows. Since this web site specialises on the marine world, good information can be found in other sections. Also look at the photographic library and classifications for images of marine organisms.

there are many lands but only one sea

A long food chain

The following summary of characteristics of the seas, may give an idea how different it is from what we experience ourselves on land.

f019624: zoanthid anemones on a red carpet sponge.
f019624: yellow zoanthid anemones on a red carpet sponge, in New Zealand. The ocean has life forms that have not become terrestrial. 
f020710: a Diadema palmeri sea urchin
f020710: A Diadema palmeri sea urchin at the Poor Knights Islands, New Zealand. Sea urchins, starfish and other echinodermata are not represented on land or in fresh water.
Marine threatened species
species status comment conservation
Triton's trumpet (giant triton) Charonia tritonis rare A very large tropical shell, reaching 40cm length. It is collected for the ornamental shell trade. Living in shallow water, these shells are easy to collect. In Indonesia, a survey of 133 sites on 92 reefs, found only 2 individuals. Protected in Australian waters, Seychelles and Fiji.
Giant clam Tridacna gigas vulnerable The largest living shelled mollusc, measuring up to 1.3m and weighing over 200 kg, of which 60 kg is living tissue. Giant clams may live for 100 years or more. Giant clams live in shallow water and are easy to harvest for food. They are also collected for their ornamental shells. Fully protected in Australia, Papua New Guinea. Proposed for Appendix 2 of CITES.
Coconut crab Birgus latro rare The largest terrestrial arthropod in the world, measuring up to 1m between stretched legs, weighing up to 3 kg. A tropical (hermit) crab, which has abandoned the sea, except that females have to return to the sea to lay their eggs. The crab is regarded as both an aphrodisiac and delicacy by islanders, who hunt it persistently. Also predated upon by introduced species like rats, pigs and monkeys. Fully protected on Aldabra (Indian Ocean). Further proposals for protection elsewhere.
Threatened species: some tuna, some sharks, some salmon, all turtles, many sea mammals.

Also read the section on oceanography which gives further background information on the physics and productivity of the oceans.
For more details on marine habitats and living in the sea, read marine environment/habitats/introduction.
Thorne-Miller, Boyce & John Catena (1991): The living ocean: understanding and protecting marine biodiversity. Island Press.

go to part1 (content) <==> go to part2 <=> go to part4