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►Subphylum Vertebrata
►Sharks and Rays-Teeth and Wings
►Ray-Finned Fish-Half the World’s Vertebrates
►Marine Reptiles-Cold Blood and Warm Water
►Seabirds-At Flight Over and In the Ocean
►Marine Mammals-Warm Blood in Cold Water
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Subphylum Vertebrata
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Subphylum Vertebrata
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Characteristics of Vertebrates
Organisms in this subphylum:Dominate the upper levels of almost all food webs.Have a dorsal nerve cord that has developed into
a spinal cord, protected by vertebrae.Have a head with a brain.Are complex, large, fast, and
conspicuous organisms. Includes man.
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Jawless Fish - The Living Ancestors of Sharks and Fish
Jawless fish, the agnathans: Includes two classes Perromyzontida - the lampreys, and
Myxini - the hagfish. May represent the ancestor of ray-finned fish and sharks. Scientists theorize that during the Cambrian period the first
of three gill arches on a jawless fish evolved into the first jaws.
Having jaws allowed vertebrates to become very successful predators.
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Sharks and Rays - Teeth and Wings
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Characteristics of Sharks and Rays
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Characteristics of Sharks and Rays
Class Chondrichthyes includes sharks, rays and their close relatives.Sharks and rays don’t look similar on the outside,
but share a basic anatomy that classifies them together.
Sharks and rays are jawed fish, that lack a swim bladder, and have cartilaginous skeletons - they lack true bone.
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Special Attributes of Sharks and Rays
Sharks and rays:Are in the subclass Elasmobranchii.Are energy-efficient - don’t have to eat as
much as other organisms the same size. Because of this they are successful predators.
Have relatively simple cartilaginous skeletons - lighter than bone; saves energy.
Store low-density oils for buoyancy.Have fins or wings that sit at angles and act like
wings to provide lift.Skin contributes to saving energy.Have a “conveyor belt” of multiple rows of teeth.S
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Special Attributes of Sharks and Rays
Sharks and rays have other interesting characteristics:Both have lateral lines – lines of sensory hair
along the length of the body that detect water motion and vibrations.
Unique to elasmobranchs is electroreception – the ability to sense minute electricity created by muscles and nerves.
Sharks and rays have organs called ampullae of Lorenzini which you can see as visible pits near their snouts used to detect the electrical current.
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Special Attributes of Sharks and Rays
Shark Anatomy
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Special Attributes of Sharks and Rays
Elasmobranchs differ in their reproductive strategy. Sharks and rays produce fewer, but more mature offspring. Most fertilize their eggs internally.
The male deposits sperm in the female via a pair of copulatory organs called claspers found at the base of the pelvic fins.
The female lays an egg case in which the juveniles develop for up to six months at which time one or more sharks or rays emerge.
A few shark species are ovoviviparous – the eggs hatch within the mother’s body. They give birth to live young rather than egg cases.
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Special Attributes of Sharks and Rays
Shark Egg CaseFrom An Oviparous Species
Shark ClaspersOn A Male
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Special Attributes of Sharks and Rays
Small and large sharks. Most sharks are not “man-eaters.” Many species of sharks
are small. Shark size ranges from hand-sized to the
whale shark – the largest fish in the ocean. Whale sharks can reach 14 meters (46 feet). Basking sharks can reach 10 meters (33 feet). Megamouth sharks can reach 6 meters (20 feet).
All three of these large sharks are filter feeders that consume plankton.
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Special Attributes of Sharks and Rays
Horned SharkThis California species isless than two feet long as
an adult.
Whale SharkThe largest fish in the ocean.
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The Predators’ Predator
The shark family Lamnidae are famous for their size and abilities.
Family includes makos, porbeagles and great whites. These sharks:
Are partially warm-blooded - large powerful muscles. Have efficient swimming shapes. Are at the top of the food web - an apex predator. Are in danger of extinction from man.
Mako Great White
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Special Attributes of Rays
Superorder Batidoidimorpha of subclass Elasmobranchii consists of the rays, which includes skates, mantas and guitarfish.
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Special Attributes of Rays
Rays:Have an anatomy well suited to life on sandy
bottoms or midwater.Are specially adapted to life in midwater are the
eagle ray and manta ray.Have pectoral fin “wings” that stretch forward over
the gills and are fused to the sides of the head.Shoulder girdles are flattened and many bones
are fused together for rigidity.
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Special Attributes of Rays
Rays:No longer need a tail for swimming, the tail has
become a defensive whip in some species.Literally fly through the water. Include the mantas with wingspans exceeding 8
meters (26 feet). Mantasfeed on plankton likemany other largerorganisms in the ocean.
Eagle Ray
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Ray-Finned Fish - Half the World’s Vertebrates
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Characteristics of Ray-Finned Fish
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Characteristics of Ray-Finned Fish
Superclass Osteichthes and Class Actinopterygii are the “bony” or “ray-fin” fish. They are jawed fish with bone skeletons. Most have a swim bladder and scales. Most control buoyancy by adding or releasing gas to/from
their swim bladder. They control the swim bladders with oxygen gas
exchanged to and from blood circulation. Many have a special organ called the gas gland and the
rete mirabile that take up gases from the bloodstream for the swim bladder.
This allows many species to hover nearly motionless in midwater.
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Characteristics of Ray-Finned Fish
Most ray-finned fish reproduce externally.The female lays her eggs, usually in vast numbers
that can reach millions in some cases.The male immediately fertilizes them.Some species protect the eggs and juveniles,
others leave larvae to fend for themselves as plankton.
The strategy here is to produce a vast number of off-spring with only a few expected to survive to maturity. Contrast this with elasmobranchs.
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Characteristics of Ray-Finned Fish
Basic Ray-Finned Fish Anatomy
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Characteristics of Ray-Finned Fish
Ray-finned fish have characteristics for life on the reef and for life in the open ocean:Ray-finned fish have lateral lines that detect water
motion and vibrations.Most open ocean and schooling fish are relatively
similar in shape and coloration.Fusiform shape - spindle form, broader at the
head, and V-shaped tail. As in tuna.Countershaded for concealment - dark on top,
light on the bottom.
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Characteristics of Ray-Finned Fish
Fast FishTuna adapted to the open ocean life.
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Characteristics of Ray-Finned Fish
Ray-finned fish have adapted to many diverse bottom and reef habitats as well as midwater habitats.
Survival strategies are likewise diverse - concealment, armor and fast swimming.For protection, reef and bottom species have far
more diversity in color, shape, and size than midwater fish.
AngelfishTall narrow bodies. They can turn quickly and maneuver down into narrow cracks to hunt prey and
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Characteristics of Ray-Finned Fish
Moray EelElongated, snake-like body
for living in crevices and small caves
FounderFlat body for
living concealed on the bottom.
Squirrel FishA nocturnal fish with a red color that helps it remain concealed at
night.
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Special Attributes of Orders Clupeiformes and Gadiformes
Two orders in class Actinopterygii have an importantplace in worldwide fisheries. Order Clupeiformes which includes herrings, pilchards,
sardines, and anchovies. About one-quarter of all fish caught come from this order.
Order Gadiformes which includes cods, pollocks, haddock, whitings, and their relatives. This order continues to produce about a sixth of the
world’s fish catch. Alaskan pollack, the haddock and whitings have become
important fisheries. Historically, worldwide fisheries have influenced politics and
caused wars.
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Special Attributes of Orders Clupeiformes and Gadiformes
ClupeiformesAnchovies
GadiformesHaddock
GadiformesCod
GadiformesPollock
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Marine Reptiles - Cold Blood andWarm Water
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Characteristics of Reptiles
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Characteristics of Reptiles
Organisms in class Reptilia mostly live on land or in freshwater. Relatively few live in the ocean. They have these characteristics in common:Are generally cold-blooded and have scales.Reproduce (most species) by laying internally
fertilized eggs. Breathe air with lungs at all stages of their lives.
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Special Attributes of Marine Crocodiles,Turtles, Snakes, and Lizards
Three orders of reptiles having marine species are: Order Crocodilia – alligators, crocodiles, and caimans.
Members of this order are semi-aquatic with most living in freshwater. Exception is the giant saltwater crocodile.
Order Chelonia – turtles and tortoises. There are seven species of marine turtles – all live in
relatively warm waters. Most are endangered. Order Squamata – snakes and lizards.
61 species of sea snake are true marine organisms. Only one lizard is a true marine reptile – the marine iguana.
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Special Attributes of Marine Crocodiles,Turtles, Snakes, and LizardsOrder Chelonia – Marine Turtles
Green sea turtle.Photo from Belize,
Caribbean.
Hawksbill turtle.Cayman Islands,
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Special Attributes of Marine Crocodiles,Turtles, Snakes, and LizardsOrder Chelonia – Marine Turtles
Leatherback turtlefitted with a tracking
transmitter.
Nesting femalesea turtle.M
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Special Attributes of Marine Crocodiles,Turtles, Snakes, and Lizards
Order Squamata - Snakes and Lizards
Sea snakes.True marine organisms;
known for having the mosttoxic venom of any snake.
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Special Attributes of Marine Crocodiles,Turtles, Snakes, and Lizards
Order Squamata - Snakes and Lizards
Marine iguanas.A single species of
marine iguanas, found on the Galapagos Islands.
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Seabirds - At Flight Over and In the Ocean
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Characteristics of Birds
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Characteristics of Birds
Birds are vertebrates in class Aves. They share several characteristics: Feathers, unique to this class. Forelimbs that are wings. A four-chambered heart and lay internally fertilized eggs.
Marine birds are important to the marine ecosystem: They are predators that consume fish, crustaceans, and
mollusks. In turn they are prey to marine mammals and sharks. They supply guano – a significant source of nutrients,
specially organic nitrogen important to sea life.
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Characteristics of Birds
Many species of birds exhibit related adaptations to an aquatic life:Webbed feet for swimming and floating on the
surface.Bill adaptations suited to catching their marine
prey, like the pelican’s pouch.The cormorant flies over water, and dives in it in
pursuit of prey.Birds, like the albatross, have wings and flight
characteristics adapted to long-duration flying over wide expanses of water.
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Special Attributes of Penguins
Penguins, order Sphenisciformes, all live in the Southern hemisphere.
Penguins make up about 80% of all Antarctic birds and by far outnumber even the massive marine mammal populations.
Emperor Penguins.Adapted to a totallymarine existence.
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Special Attributes of Penguins
Penguins, order Sphenisciformes, all live in the Southern hemisphere.
Penguins make up about 80% of all Antarctic birds and by far outnumber even the massive marine mammal populations.
Not all species live in cold places. Penguins are found on the coasts of South America, Africa,
Australia, New Zealand, and the nutrient-rich waterssurrounding the Galapagos Islands near the equator,
They cannot fly, but they’re as at home underwater as other birds are in the air. They: Spend as much as 75% of their time under water searching
for food. Can reach depths of 100 meters (328 feet) and deeper.
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Marine Mammals - Warm Bloodin Cold Water
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Characteristics of Marine Mammals
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Characteristics of Marine Mammals
All organisms in class Mammalia share these characteristics. They:Have hair on some part of the body.Nourish their young with milk provided by
mammary glands.Are homeothermic (warm-blooded) with a
constant internal temperature.Give birth to live young (majority of species).
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Characteristics of Marine Mammals
The marine environment poses FIVE main challenges to mammalian physiology: 1. Compared to living in air, life in water demands high
oxygen consumption. Marine mammals meet this challenge by breathing air.
2. There is a need to dive holding their breath for reasonable periods. They: Use myoglobin, a protein, to bind reversibly with oxygen
to make it available for use in metabolism. Use the mammalian diving reflex – is when diving pulse
rate slows and blood flow diverts from the muscles to the heart and brain.
Sink or glide underwater reducing oxygen use.
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Characteristics of Marine Mammals
3. The water pressure and a need to equalize. Marine mammals’ lungs and sinuses are very flexible,
allowing compression without pain or injury. Some dolphins and whales have lungs that engorge with
blood thus offsetting the compressed space. 4. The challenge of easy movement through the dense
medium of water. The use of streamlining and hydrodynamics helps with
this.
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Characteristics of Marine Mammals
5. The challenge of the senses. They need to hear, see, and smell underwater. Dolphins and whales use echolocation (natural sonar) to
determine distance, size, density, and shape. Seals and sea lions have sensitive hearing and excellent
underwater eyesight. They see poorly above water, but have a keen sense of smell.
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Special Attributes of Seals and Sea Lions
The seals and sea lions belong in order Pinnipedia. “True” Seals: don’t have ear flaps, rear flippers
point backward and cannot rotate forward, out of water seals crawl on their stomachs.
Sea Lions: have ear flaps, hindflippers rotate, can sit uprightand run.
Walrus: don’t have ear flaps,hind flippers rotate, cansit upright.
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Special Attributes of Dolphins, Whales and Porpoises
Whales, porpoises, and dolphins come from different families organized under the order Cetacea. Cetaceans are divided into two suborders: Suborder Mysticeti: a group of filter feeders made up of
baleen whales. Suborder Odontoceti: a group of toothed whales made up of
sperm whales, dolphins and porpoises. They are predators. Family Delphinidae: are the dolphins and orcas, one of
the most varied and successful groups among the toothed whales.
Most cetacea use echolocation and communicate by sound.
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Special Attributes of Dolphins, Whales and Porpoises
Relative sizes of the baleen whales in the
suborder Mysticeti.
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Special Attributes of Dolphins, Whales and Porpoises
Relative size of toothed whales in
the suborder Odontoceti.
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6 t
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27
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7 - 55
Special Attributes of Dolphins, Whales and Porpoises
Bottlenose DolphinsFamily Delphinidae
OrcaKiller Whale
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Special Attributes of Dugongs and Manatees
Dugongs and manatees (sometimes called sea cows)belong to order Sirenia, which has four species.All four are the only herbivorous marine mammals.Manatees are known for migrating to and from
fresh- and saltwater environments.Relatives of the elephant. They are endangered.
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Marine Mammals and Human Interaction
Human activities have endangered marine mammals and continue to do so.Whaling brought whales to the verge of extinction.
Banned or greatly limited by international convention today, some species seem on the rise, others do not seem to be recovering.
Old-school whaling
operation.
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7-2
8 t
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7 - 58
Marine Mammals and Human Interaction
Human activities have endangered marine mammals and continue to do so. People have hunted seals for their fur and manatees for
meat. Dolphins have been killed as bycatch in tuna fishing. Pollution and overfishing raise new threats.
Because of their high metabolisms and energy demands, marine mammals require highly productive environments to survive.
Ma
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8 t
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