Life in the Ocean

Three Groups of Marine Life

• Plankton – organisms that float near the ocean’s surface – mostly microscopic– Phytoplankton: plantlike– Zooplankton: animal-like

Three Groups of Marine Life

• Nekton – free swimming organisms of the oceans (mammals, whales, dolphins, sea lions, fish).– Most abundant in

surface water

Three Groups of Marine Life

• Benthos – organisms that live on the ocean floor in mud, sand & rock.– crabs, sea stars, worms, coral, sponges,

seaweed, clams

Benthic Environment

• The ecological zone of the ocean that includes the ocean floor and all the organisms that live on or in it

• Divided into different zones based on depth– Intertidal– Sublittoral– Bathyal– Abyssal– Hadal

Intertidal Zone• Located between the low- and high-

tide limits– Is covered with water twice a day as the

tides change– The organisms that live in this zone

must be able to breathe underwater and on land

– Must be able to keep from being washed out with the tide.

– Clams, oysters, barnacles, crabs, starfish, sea anemones

Sublittoral Zone

• Begins at the low-tide limit and extends to the edge of the continental shelf– Depths reach to 200 m– Temperature, water pressure, sunlight

are fairly constant– Most animals stay in the upper 100 m to

reach the sunlight

Bathyal Zone

• Extends from edge of continental shelf to abyssal plain– 200 m – 4,000 m – Lack of sunlight = few plants– Animals include: sponges, brachiopods,

sea stars, echinoids, octopuses

Abyssal Zone

• Scientist know very little about this zone– Very deep and dark– 4,000 and below – can reach 6,000 m– Few animals/ no plants– Some crabs, sponges, worms, sea

cucumbers– Live around hot-water vents & in

extreme conditions

Hadal Zone

• The deepest benthic zone• Consists of deepest ocean floor and

trenches• Less is known about this zone than

the abyssal zone• Few animals: a type of sponge, a few

worms, a type of clam

The Pelagic Environment

• The environmental zone that includes the entire volume of water in the ocean and the marine organisms that live above the ocean floor

• Two major zones– Neritic Zone– Oceanic Zone

Neritic Zone

• Includes the volume of water that covers the continental shelf

• Warm, shallow zone• Largest concentration of marine life

– Lots of sunlight– Lots of benthos to serve as food

• Fish, plankton and marine mammals

Oceanic Zone

• Includes the volume of water that covers the entire sea floor except for the continental shelf

• In deeper parts, the temperature is colder and the pressure is greater

• Organisms spread out more• Some animals include giant squid,

whales

Resources

• http://www.beachwatchers.wsu.edu/ezidweb/animals/• http://go.hrw.com• http://marinebio.org/species.asp?id=33• http://waynesword.palomar.edu/algae1.htm• http://www.seasky.org/reeflife/sea2a.html• http://paleo.cortland.edu/tutorial/Brachiopods/brachiopoda.

htm• http://www.bisdragons.com/students2001/oceans/abyssalpl

ains/animals.html• http://www.marksmarine.net/encylo/clown/clown_fish.htm• http://www.whales.org.au/gallery/index.html