A community is a group of organisms that interact in a specific place. Pelagic organisms, those that live suspended in the water, compose one of the ocean''s largest communities.

Planctonic organisms drift or swim weakly; nectonic organisms actively swim.


The term plancton is not a collective natural category; it is a description of a lifestyle. Plancton is made up of many plantlike species and nearly every major group of animals.

Phytoplancton: The Autotrophs
Diatoms (frustile, valves, siliceous ooze)
Dinoflagellates (flagella, guring a red tide, the presence of millions of dinoflagellates turns seawater brownish red, red tide, bioluminescence)
Coccolithophores and others (nanoplancton, ooze deposits, White Cliff of Dover in England, and the extensive chalk deposits of northern Texas)

The plantlike organisms that make up the phytoplancton are responsible for most of the ocean''s primary productivity. Of these, diatoms are the most productive and efficient.
Phytoplancton Productivity

Zooplancton : The Heterotrophs

Copepods are crustaceans, and group that also includes crabs, lobsters, and shrimp
Not all members of the zooplankton are small, and many range in size from 1-2 sm. The larger drifters are giant jellyfish of genus Cyanea (3.5 m in diameter).
-microplancton and macroplancton.
Most zooplankton spend their whole lives in the plankton community – holoplancton
Temporary visitirs – meroplancton
Krill (genus Euphausia)
A foraminiferan (deposits of ooze)

Plankton and Food Webs

NECTON (fish and mammals)

Squids and Nautiluses
Shrimps and Their Relatives

The Cartilaginous Fishes
The Bony Fishes
The Problems of Fishes
Marine Reptiles
Marine Birds
Marine Mammals

The Animal Kingdom
Phylum groups together organisms with similar body organization, level of complexity, and evolutionary history. There are 10 common phyla in the animal kingdom with marine subjects.

1. Protozoa ------Amoeba, foraminifera, radiolaria

2. Porifera -----Sponges

3. Cnidaria -----Coral, Jellyfish, sea anemones.

4. Platyhelminthes--- Flatworms, tapeworms.

5. Nematoda----- Roundworms.

6. Annelida----- Segmented worms (nereis).

7. Mollusca---- Snails, squids, bivalves, octopus

8. Arthropoda---- Crabs, shrimp, barnacles, krill.

9. Echinodermata---- Sea urchins, sea stars, sea
10. Chordata---- Tunicates, fish, birds, reptiles,

Collecting and Studuing Plancton
Plancton nets
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words phyton, or "plant", and рлбгкфпт ("planktos"), meaning "wanderer" or "drifter".[1] Most phytoplankton are too small to be individually seen with the unaided eye. However, when present in high enough numbers, they may appear as a green discoloration of the water due to the presence of chlorophyll within their cells (although the actual color may vary with the species of phytoplankton present due to varying levels of chlorophyll or the presence of accessory pigments such as phycobiliproteins, xanthophylls, etc.).

Ocean color and phytoplancton productivity
In the tropics?
In the polar regions?
In the temperate and subpolar zones?
250 gC/m3/yr!
Does productivity change with the seasons?

Most primaru productivity occurs above the continental shelves of the temperaturew zones and in the southern subpolar zones.

New System Can Measure Productivity Of Oceans

Protozoan Plankton Ecology By Johanna Laybourn-Parry

Plankton and food webs

The mollusks (with clams and snails) are the cephalopods (squids, nautiluses and octopuses).

The cephalopods (Greek plural Κεφαλόποδα (kephalópoda); "head-feet") are the mollusc class Cephalopoda characterized by bilateral body symmetry, a prominent head, and a modification of the mollusk foot, a muscular hydrostat, into the form of arms or tentacles. Teuthology, a branch of malacology, is the study of cephalopods.

The class contains two extant subclasses. In the Coleoidea, the mollusk shell has been internalized or is absent; this subclass includes the octopuses, squid, and cuttlefish. In the Nautiloidea the shell remains; this subclass includes the nautilus. About 800 distinct living species of cephalopods have been identified. Two important extinct taxa are Ammonoidea, the ammonites, and Belemnoidea, the belemnites.

Cephalopods are found in all the oceans of Earth, at all depths. None of them can tolerate freshwater, but a few species tolerate more or less brackish water.

Introduction to Cephalopods: octopus, squid, cuttlefish and nautilus

Welcome to CephBase of James B. Wood
Invertebrates are soft-bodied animals that lack a rigid, internal skeletal support, they are protected in some of these organisms by an exoskeleton. Exoskeletons are composed of various materials from limestone, silica, to chitin.

Because the invertebrate grouping is not based on lineage or common ancestry, most animals on earth are in this group. In fact, 90% of extinct and living animals are invertebrates. Today here are 33 invertebrate phyla and nearly all of them have marine relatives. Only the phylum Chordata is unusual because its members are recognized by the presence of a stiff rod called the notochord during embryonic development. A few of them lose the notochord as adults. These are the invertebrate chordates. But the 95% that retain it into adulthood are called vertebrates.

In general, invertebrates have evolved from single-celled forms (protozoans) through colonial forms (cnidaria -corals), to true multicellular forms such as shrimps. The trend in evolution also included a change in body symmetry - from radial to bilateral. In this order of ever increasing complexity, the worm phyla was the earliest group to produce important features of advanced design:

* Bilateral symmetry, except for echinoids.
* Development of a brain (area of concentrated sense cells).
* A linear digestive system (separate anus and mouth).
* Segmentation, an important way of improving articulation and body size.
* Development of circulatory and excretory systems.

The vertebrates are the predominant members of the phylum chordata (95%). These animals possess an endoskeleton of bone and cartilage. This skeletal structure allows advanced animal design features such as:

* Uninterrupted support during growth,
* Protection of soft organs,
* The foundation surface for muscles and movement,
* Protection of the largest and most advanced brains.

The main groups are: fish, amphibians, reptiles, birds, and mammals. Fish has been the most successful group in the marine environment, whereas amphibians have been the least successful group. Indeed, amphibians, reptiles, birds, and mammals, all evolved from a more primitive ancestral fish.

Almost all nektons are vertebrates except for a few invertebrates such as squids.

There are 3 groups (classes) of fish:

1. Jawless fish (Agnathans) - lampreys and hagfish.
2. Chrondicthyes ( cartilage)- sharks, skates, and rays.
3. Osteichthyes (bony) - eels, snapper, grouper, salmon.

Fish are ectothermic and completely aquatic. Forty percent of fish species are marine, and 60 % are freshwater types. Fish live at all depths in the ocean. They have fins for swimming and gills for breathing, except for a few lungfish. The period from 400 million years to 360 millions years ago is known as the Age of Fishes.

The agnathians are the most primitive vertebrates as they lack jaws and teeth. They feed by using a rasping tongue and by suction. The other groups of fish have jaws, teeth, and paired fins. The fins are used to steer, turn, brake, and balance the fish. Hence, they have been more successful at feeding on shelled invertebrates than the jawless fish.

Chondrichthyes have no bone but instead have a stiff, elastic material called cartilage. They are typically larger than bony fishes and the whale shark (up to 60 feet long) is the largest fish in the world. They also have hard, tooth-like scales and their skins have been used as "sandpaper" in the past. They predominantly live in the marine environment. Rays and skates are mostly benthic, whereas sharks are nektons. Most of this group tend to be viviparous (live births). Some sharks are very good predators having an electromagnetic sensor used to locate preys. Only 10 % are aggressive to humans including the white sharks such as the Great whites. Tiger sharks, bull sharks, and hammerhead sharks are also dangerous. For additional information, go to:

The bony fishes (ostheichthyes) are 95% of all fish and the most common among vertebrates. They are also the most diverse group among fishes. They include air-breathing lungfish and the lobed-finned coelacanths whose ancestors ventured on land and gave rise to amphibians. They are typically oviparous (egg-births). The common bony fish that are popular human food are the ones that live in the photic zone including sardines, anchovies, herrings, markerel, swordfish, and tuna. Those that live in the disphotic zone tend to have bioluminescent features.

Marine Amphibians
Amphibians are ectothermic, air-breathing, with porous skin. There are no known marine amphibians except for a few Asian frogs that tolerate up to 28% salinity for extended periods of time. In general, amphibian skins are too porous to survive marine salinity (osmotic) problems. Hence they are the least successful marine vertebrates.

Marine Reptiles
All reptiles are ectothermic, air-breathing, with impermeable, scaly skin. As a result, marine reptiles generally live in tropical and subtropical oceans. There are 4 groups of marine reptiles: crocodiles, sea snakes, iguanas, and sea turtles.

Most reptiles evolved on land and later, moved to the marine environment where they spend most of their time feeding and growing. Because most are oviparous, most have to return to land to lay and hatch their eggs. Sea turtles typically return to the beaches where they were born to lay their own eggs, approximately every 2 - 4 years. They leave their eggs in small holes on the beach to hatch on their own. The young turtles typically leave their nest at night to avoid predators and return to the ocean. Most sea snakes give live birth to their offsprings. Sea snakes are considered the most poisonous of all marine animals and live in the Pacific and Indian Oceans only.

Marine reptiles are specially equipped with salt glands to concentrate and dispose of excess salts from their body fluids.

Marine Birds
Birds evolved form a group of reptiles and still carry some features that are typically reptilian:

* Scaly legs
* Claws, and
* Egg-laying mode of reproduction.

But birds have many nonreptilian features:

* Endothermic temperature control.
* Feathers, instead of scales, is used to insulate their bodies.
* Thin, hollow bones to facilitate flying.

Only 3 % of all known birds are marine and most of them live in the southern hemisphere. There are 4 types of marine birds: albatross/petrels, pelicans, gull/terns/puffins, and penguins. All marine birds spend some time in the ocean, but all return to lay and hatch their eggs, as well as, care for their juveniles on land.

Because they feed primarily in salt water, they have special salt-secreting glands on their heads to rid of the excess salt.

The penguins are flightless birds with reduced wings shaped to enhanced their swimming ability. They carry fat in their bones and other tissues - an adaptation to cope with the harsh, cold climatic conditions they live in. Some, like the Emperor Penguin, can be up to 3 feet tall and weighing more than 80 pounds. They are so well adapted to the harsh cold that they are the only species to remain on Antarctica during winter to lay and incubate their eggs.

Marine Mammals
Mammals are also endothermic air-breathers that evolved from reptiles about 200 m.y. ago. However, no marine mammals are known before 60 m.y. ago. So it is accepted that marine mammals evolved directly from their land relatives before they attempted to live in or by the oceans.

There are 3 groups of marine mammals: 2 coastal or shallow-water types and one deep or true marine mammal group:

An arthropod is an invertebrate that has an exoskeleton (external skeleton), a segmented body, and jointed attachments called appendages. Arthropods are animals belonging to the Phylum Arthropoda (from Greek ἄсиспн arthron, "joint", and рпдьт podos "foot", which together mean "jointed feet"), and include the insects, arachnids, crustaceans, and others. Arthropods are characterized by their jointed limbs and cuticles, which are mainly made of б-chitin; the cuticles of crustaceans are also biomineralized with calcium carbonate. The rigid cuticle inhibits growth, so arthropods replace it periodically by molting. The arthropod body plan consists of repeated segments, each with a pair of appendages. It is so versatile that they have been compared to Swiss Army knives, and it has enabled them to become the most species-rich members of all ecological guilds in most environments. They have over a million described species, making up more than 80% of all described living species, and are one of only two groups very successful in dry environments – the other is amniotes. They range in size from microscopic plankton up to forms a few metres long.
By nearly any measure, the most successful animals on the planet are the arthropods. They have conquered land, sea and air, and make up over three-fourths of all currently known living and fossil organisms, or over one million species in all. Since many arthropod species remain undocumented or undiscovered, especially in tropical rain forests, the true number of living arthropod species is probably in the tens of millions. One recent conservative estimate puts the number of arthropod species in tropical forests at 6 to 9 million species (Thomas, 1990).

Arthropods range in distribution from the deep sea to mountain peaks, in size from the king crab with its 12-foot armspan to microscopic insects and crustaceans, and in taste from chocolate covered ants to crawfish jambalaya and lobster Newburg. Despite this unbelievable diversity, the basic body plan of arthropods is fairly constant. Arthropods have a stiff cuticle made largely of chitin and proteins, forming an exoskeleton that may or may not be further stiffened with calcium carbonate. They have segmented bodies and show various patterns of segment fusion (tagmosis) to form integrated units (heads, abdomens, and so on). The phylum takes its name from its distinctive jointed appendages, which may be modified in a number of ways to form antennae, mouthparts, and reproductive organs

Register of marine species

Prawns are Decapods, belonging to the sub-order Dendrobrachiata [1]. They are similar in appearance to shrimp, but can be distinguished by the gill structure which is branching in prawns (hence the name, dendro=“tree”; branchia=“gill”), but is lamellar in shrimp. The sister taxon to Dendrobranchiata is Pleocyemata, which contains all the true shrimp, crabs, lobsters, etc.
Fishes: Chondrichthyes

Introduction to the Chondrichthyes

Class Chondrichthyes (rays, sharks, and relatives)
"Great white" redirects here. For other uses, see Great White (disambiguation).
Great white shark
Fossil range: 15.970–0 Ma PreЄЄOSDCPTJKPgNMiocene to Recent[1]

Conservation status

Vulnerable (IUCN 2.3)
Scientific classification
Kingdom: Animalia

Phylum: Chordata

Class: Chondrichthyes

Subclass: Elasmobranchii

Order: Lamniformes

Family: Lamnidae

Genus: Carcharodon
Smith, 1838
Species: C. carcharias

Binomial name
Carcharodon carcharias
(Linnaeus, 1758)

Range (in red)

Sharks portal

The great white shark, Carcharodon carcharias, also known as white pointer, white shark, or white death, is an exceptionally large lamniform shark found in coastal surface waters in all major oceans. Reaching lengths of more than 6 metres (20 ft) and weighing up to 2,250 kilograms (4,960 lb), the great white shark is arguably the world''s largest known predatory fish. It is the only surviving species of its genus, Carcharodon


Bony Fish

Bony Fish: Osteichthyes

Bony Fish: Marine station

Vertebrate Evolution
Four Extant Groups of Vertebrates.
Agnatha - jawless fish.
Chondrichthyes - cartilaginous fishes (sharks and rays).
Osteichthyes - bony fish.
Tetrapods - amphibians, reptiles, birds, mammals

The major features of vertebrate evolution are shown in (Figure 2). Principal points are as follows:
First fish lacked jaws.
Belong to the class, Agnatha.
Principal fossil representatives belonged to the group called ostracoderms - heavily armored with bone.
Living species (hagfish, lamprey) belong to the group called cyclostomes.
Cyclostomes lack bony skeletons, in which regard, they are probably degenerate.
Jaws first appear in an extinct group called placoderms.
Some had paired fins.
Included parrot-beaked arthrodires

Modern fish derive from placoderm ancestors and are divided into
Figure 2. Bony fish evolution.
Chondrichthyes (cartilaginous fishes) - sharks and rays.
Osteichthyes (bony fishes) - everything else above cyclostomes

Question: If cartilaginous fish derive from placoderms, what does this say about the absence of bony skeletons in sharks and rays?
Among bony fish (Figure 2), the basic split is between actinopterygians (ray-fin fishes) and sarcopterygians (lobe-fin fishes).
Actinopterygians include
Extinct paleoniscoids and the modern birchir (Polypertus).
Sturgeons (Scaphyrhynchus) and paddlefish (Polydon).
Holosteans [gar pike (Lepidosteus) and bowfin (Amia).]
Teleosts (vast majority of contemporary freshwater and marine fishes).
Sarcopterygians include
Rhipidistians, the ancestors of all tetrapods.
Coelacanths, a marine offshoot of the basal stock, of which a single genus, Latimeria, survives as a much-modified deep sea form.
African and Australian lungfish.

Actinopterygians evolved in freshwater. Re-invaded marine environments during the Mesozoic, in which regard their success may have contributed to the extinction of ichthyosaurs.
Primitive actinopterygians had lungs (Figure 3), a character probably inherited from their placoderm ancestors.
The ancestral condition probably resembled that observed in the chondrostean, Polypterus, wherein a bilobed, ventral lung connected to the pharynx allows for respiratory function in times of drought.
In most living bony fish, the connection has been lost and what is now a swim bladder contains specialized tissue that secretes or resorbs gas.
In sum, lungs came first: swim bladders evolved from lungs, not vice versa.
Undoubtedly retained the primitive ventral lung, which, as it developed highly vascularized internal foldings, became the animal''s principal respiratory organ.
Paired fins evolved into legs (Figure 4).
Ancestral to the labyrinthodont amphibians, so named because of the elaborate labyrinthine folding of the enamel in the teeth, a character which they share with their Crossopterygian ancestors and reptilian descendants.
Other shared crossopterygian-amphibian characters:
Hinged braincase (functional in crossopterygians; nonfunctional in primitive amphibians) facilitated more powerful biting in Crossopterygian and coelacanths.
Internal nares.
"Pineal" eye.
Amphibians gave rise to primitive reptiles from which evolved
Contemporary reptiles.
Archosaurs - dinosaurs and birds

Key to the transition to a fully terrestrial existence were the evolution of a water impermiable integument and the amniote egg.

The transition from water to land posed challenges to all the major organ system. In future lectures we will focus on
Gas exchange.
Salt and water balance.


Teleostei is one of three infraclasses in class Actinopterygii, the ray-finned fishes. This diverse group, which arose in the Triassic period[1], includes 20,000 extant species in about 40 orders; most living fishes are members of this group.[2] The other two infraclasses, Holostei and Chondrostei, are paraphyletic

Some of the diversity exhibited by teleost bony fishes. Lionfish, Scrawled cowfish, weedy seadragon, redfish, sunfish, morau eel are not all drawn to the same scale.

Photos of marine creatures

Introduction to Chelonia
Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semi-aquatic life in a marine environment.

The earliest marine reptiles arose in the Permian period during the Paleozoic era. During the Mesozoic era, many groups of reptiles became adapted to life in the seas, including such familiar clades as the ichthyosaurs, plesiosaurs, placodonts, and mosasaurs.

After the mass extinction at the end of the Cretaceous period, marine reptiles were less numerous. Extant marine reptiles include marine iguanas, sea snakes, sea turtles, and some species of crocodiles.

Some marine reptiles, such as ichthyosaurs and mosasaurs, rarely ventured onto land and gave birth in the water. Others, such as sea turtles and saltwater crocodiles, return to shore to lay their eggs. Some marine reptiles also occasionally rest and bask on land.

Marine reptiles

Paleontology: Marine Life in General

Global Lake Monster Database

Animals are heterotrophs that depend on other organisms for their source of nutrition. All animals have 3 fundamental tasks:

1. To find food.
2. To avoid predators.
3. To reproduce.

Indeed, most animal adaptations are geared toward meeting these goals.


Order Carnivora

Carnivora -wiki

Cetacea - wiki: whales, dolphins and porpoises
This article is about the order Cetacea. For the song by Icelandic singer Björk, see Drawing Restraint 9 (album).
Fossil range: 55–0 Ma PreЄЄOSDCPTJKPgNEarly Eocene - Present

Humpback Whale breaching
Scientific classification
Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Infraclass: Eutheria

Superorder: Laurasiatheria
(unranked) Cetartiodactyla
(unranked) Whippomorpha

Order: Cetacea
Brisson, 1762

Around 88 species; see list of cetaceans or below.
Archaeoceti (extinct)
(see text for families)

The order Cetacea (IPA: /sɪˈteɪʃiə/, L. cetus, whale, from Greek) includes whales, dolphins, and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal", was more general. It comes from Ancient Greek κῆτος (kētos), meaning "whale" or "any huge fish or sea monster". In Greek mythology the monster Perseus defeated was called Ceto, which is depicted by the constellation of Cetus. Cetology is the branch of marine science associated with the study of cetaceans.

Cetaceans are the mammals best adapted to aquatic life. Their body is fusiform (spindle-shaped). The forelimbs are modified into flippers. The tiny hindlimbs are vestigial; they do not attach to the backbone and are hidden within the body. The tail has horizontal flukes. Cetaceans are nearly hairless, and are insulated by a thick layer of blubber. As a group, they are noted for their high intelligence

Sirenia: Sirenia is an order of fully aquatic, herbivorous mammals that inhabit rivers, estuaries, coastal marine waters, swamps, and marine wetlands. The order evolved during the Eocene epoch, more than 50 million years ago. Sirenians, including manatees and the dugong, have major aquatic adaptations: forelimbs have modified into arms used for steering, the tail has modified into a paddle used for propulsion, and the hind limbs (legs) are but two small remnant bones floating deep in the muscle. They appear fat, but are fusiform, hydrodynamic, and highly muscular. Their skulls are highly modified for taking breaths of air at the water''s surface and dentition is greatly reduced. The skeletal bones of both the manatee and dugong are very dense which helps to neutralize the buoyancy of their blubber. The manatee appears to have an almost unlimited ability to produce new teeth as the anterior teeth wear down. They have only two teats, located under their forelimbs, similar to elephants. The elephants are thought as the closest living relative of the sirenians

The order Sirena

Marine and Coastal Systems
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