Marine Life and Ecology

Marine LifeMarine Lifeand Ecologyand Ecology

2.2. From phytoplanktons From phytoplanktons to invertebatesto invertebates

Virtually all primary productivity on land comes from large

plants

… seaweeds such as these do exist, but they need shallow water where

Sunlight is available and firm substrate for anchorage by their

holdfasts.

… whereas microscopic unicellular plants (diatoms, dinoflagellates) and

algae account for most of the ocean’s primary productivity.

Phylum Phaeophyta or Brown Algae

Phylum Rhodophyta or Red Algae

Seaweeds are large marine multicellular algae. These non-vascular plants are grouped as green, red and brown algae.

Phylum Chlorophyta or

Green Algae

BacteriaBacteria

Producers Producers (photosynthesizers)(photosynthesizers)

Blue-green algaeBlue-green algaeCoccolithophoresCoccolithophoresSilicoflagellatesSilicoflagellatesDiatomsDiatomsDinoflagellatesDinoflagellates

Consumers (Oxidizers)Consumers (Oxidizers)ProtozoansProtozoans

RadiolariansRadiolariansForaminiferaForaminifera

<5 <5 mm

5 5 mm3-10 3-10 mm5-40 5-40 mm

20-80 20-80 mm10-50 10-50 mm

50-500 50-500 mm100-1000 100-1000 mm

NoneNone

NoneNoneCaCOCaCO33

SiOSiO22

SiOSiO22

Cellulose Cellulose or noneor none

SiOSiO22

SiOSiO22

BenthicBenthic

Surface watersSurface waterswarm open oceanwarm open oceancool open oceancool open ocean

upwellingupwellingwarm quiet waterswarm quiet waters

Surface waters and Surface waters and sedimentssediments

Size Skeletalmaterial Habitat

Unicellular Unicellular Marine LifeMarine Life

Moss

Fern

Kelp bed

Marsh grass

0 24001600800

800

400

0

Distance from shore (km)Distance from shore (km)

Cel

l co

un

ts p

er 5

0 cm

Cel

l co

un

ts p

er 5

0 cm

33 o

f w

ater

of

wat

er

DiatomsDiatoms

DinoflagellatesDinoflagellates

CoccolithophoresCoccolithophores

SpermatophytaeSpermatophytae(seed bearing plants)

Thallophytae(algae and fungii)

SpermatophytaeSpermatophytae(seed bearing plants)

Pteridophytae(ferns)

Bryophytae(moss)

Thallophytae(algae and fungii)

Land plants Marine plants

Mangroves thrive in warm tropical waters, kelp prefers cooler waters.

Photomicrograph of tiny marine bacteria (~1 m) attached to the larger diatoms.

Cyanobacteria(x 3000 magnification)

Diatoms

CoccolithophoresCoccolithophoresCoccolithophoresCoccolithophores

DinoflagellatesDinoflagellates

Marine invertebrates Phylum Porifera (Sponges) Phylum Cnidaria

(Corals, Portugese Man-of-War, Jellyfish) Phylum Mollusca

(Clams, Snails, Octopi) Phylum Anthropoda

(Crabs, Shrimp, Lobsters, Copepods) Phylum Echinodermata

(Sea Stars, Brittle Stars) Marine worms (Polychaeta,

Vestimentifera)

Marine vertebrates

Marine animals

As Robert May (Scientific American, October 1992) has argued, most of the species display a predictable

relation between physical size and population size: the smaller they are, the more

abundant they tend to be.

Characteristic size (meters)

1 mm 1 cm 1 m

Implication: More species < 1 mm await discovery

than ones > 1 cm.

Jellyfish are cnidarians which lack the polyp stage of the life cycle. Therefore, they are always in the medusae stage. They are considered plankton because they cannot swim on their own--they are dependent upon the current to take them places. They are normally found in the epipelagic layer of the ocean.

The deep scattering layerThe deep scattering layer

Zooplankton concentration shows two peaks in the very productive summertime subarctic or cold temperate waters:

• some are feeding at the surface, while

• others are resting, or metabolizing what they have consumed, just below the photic zone.

In contrast, in the tropics, the zooplankton concentration is on the photic surface waters.

Yellow sponges on a

reef. Sponges are filter feeders

- they filter their food particles

from water that passes

through them.

An anemone is a cnidarian, a simple animal consisting of an open gut surrounded by tentacles - stinging cells in these tentacles help paralyze small prey that the tentacles then help bring into the gut.

Jellyfish, a cnidarian, consuming a fish that it has captured

Different species of jellyfish have different innate buoyancies, so when they are not swimming, some hang neutrally in the water, while others slowly sink when passive; a few float. Some of them are rather small, often less than an inch (or 2.5 cm) and also often found in freshwater as well are subject to the oceans currents, tides and waves for their large-scale movements.

But giants like the Lion’s Mane Jellyfish* are known to be excellent swimmers. This is the largest known species of jellyfish, and is mostly found in cold waters north of 42°N (Arctic, North Atlantic and theNorth Pacific) and off Australia and New Zealand. The largest recorded specimen, found washed up on the shore of Massa-chusetts Bay in 1870, had a bell (body) with a diameter of 2.3 m (7 feet 6 inches) and tentacles 36.5 m (120 feet) long. It was longer than a Blue Whale, the longest known animal in the world.

Is Jellyfish a plankton or a nekton?

* The Sherlock Holmes story, The Adventures of the Lion’s Mane, is centered around a professor who is mysteriously killed. At the end of the story, Holmes discovers the killer is a huge Lion's mane jellyfish.

A bizarre new species of jellyfish has been discovered in the deep waters off the Californian coast. The bell-shaped creature spans a meter in diameter and has been nicknamed "big red", because of its unusual deep red color. The US and Japanese teams that discovered it say the species deserves its own subfamily.

Tiburonia granrojo was discovered using video cameras on deep-diving remotely operated vehicles (ROVs). Its color and shape set it apart from its other gelatinous relatives, but it has another unusual characteristic — a complete lack of tentacles.

Bizarre new jellyfish discovered 18:03 07 May 03 NewScientist.com news service 

Orange Finger SpongePurple and Yellow Tube Sponge

Phylum Porifera

The animals of the class hydrozoa

have both a polyp and medusa

stage. Siphonophores

are a type of hydrozoan with a

float for buoyancy.

Probably the most famous of these is

the species physalia, the

Portugese-man-of-war, which is a type of colonial siphonophore.

Marine worms include

Octopus

Mussels

krill

crabs

barnacles

sea urchin

starfish

sea cucumber