Vertebrate Animals

DOMAIN- Eukarya KINGDOM- Animalia

PHYLUM- Chordata•SUBPHYLUM- Vertebrata

CLASS- 7 differentORDERS- 10 Placental mammals

Phylum ChordataRecall that vertebrates are chordates.

Phylum Chordata includes the lancelets and tunicates (invertebrate chordates) as well as the vertebrates

All chordates have:

Characteristics of all Vertebrates

Endoskeleton with a backbone for support of a dorsal nerve cord & muscle attachmentDistinct skull/cephalizationBilateral symmetry2 pairs of jointed appendagesCoelom Closed circulatory system & chambered heart

Vertebrate Evolution

Major Groups of Vertebrates• Fish – aquatic tetrapods with scales, gills, & 2 chambered hearts

• Agnathans – jawless fishes – hagfish and lampreys

• Chondrichthyes – cartilagenous fish - sharks & rays

• Osteichthyes – bony fish – mahi-mahi, tilapia, halibut, puffer fish, tetras, guppies

• Amphibians – semiaquatic tetrapods with split lives & 3-chambered hearts

• Anura – “tailless ones” – frogs & toads

• Urodela – “tailed ones” – salamanders & newts

• Apoda – “legless ones” - caecilians

• Reptiles – terrestrial amniote tetrapods with scales & lungs & 3-ish to 4 chambered hearts

• Squamata – lizards and snakes

• Testudines – turtles & tortoises

• Crocodilia – alligators, crocodiles, and related species

• Birds – terrestrial amniote tetrapods with feathers & lungs & 4 chambered hearts

• Ratites – ostriches, emus, kiwis

• Passeriformes – perching birds – jays, sparrows, crows, etc.

• Aquatic birds – ducks, swans, geese

• Raptors – eagles, falcolns, hawks

• Penguins

• Mammals – terrestrial amniote tetrapods with lungs, hair and mammary glands & 4 chambered hearts

• Monotremes – echidna and platypus

• Marsupials – koala, kangaroo, opossom

• Placentals – humans, bears, tigers, giraffes, deer, pigs, dogs, cats, raccoons, squirrels, whales, walruses, manatees, etc

Fish Vocabulary• Gill – respiratory structure that uses countercurrent exchange to extract oxygen from

water

• Operculum – gill covering in bony fish

• Lateral line - a row of microscopic organs sensitive to pressure changes, can detect low frequency vibrations.

• Swim bladder – internal, air-filled sac that acts as an organ for buoyancy in bony fish; sharks have oils in their livers to help them remain buoyant

• Scale – small, platelike structure covering an organism (or parts of an organism); sharks, fish, reptiles, and birds all have different types of scales

• Fin – paired appendage found on fish used for locomotion and steering

• Reproduction

• External fertilization – release of gametes to the environment where fertilization takes place; bony fish

• Internal fertilization – deposition of sperm in the female reproductive tract where fertilization takes place; sharks

• Hermaphrodite – some organisms are capable of producing both male and female gametes; few are capable of self-fertilization; most exchange sperm; evolutionary adaptation for solitary and slow-moving or sessile organisms

• Ovoviviparous = eggs are fertilized inside the parent and hatch inside the parent and are born live

Oviparous = eggs are laid in a nest or in the ground and hatch

Viviparous = internal fertilization with live born young (as soon as the egg is fertilized, it becomes an embryo and develops as a fetus).

Class AgnathaHagfish and lampreys

- Jawless & finless- Skeleton of

cartilage- Reproduce sexually- Gills- 2 Chambered Heart- Oviparous

Hagfish – a detritivore

Lamprey – an ectoparasite

Evolution of Gnathostomes – the

jawed fishes

Gills are supported by cartilage or bone. Some of these gill supports became other structures, including the jaws and inner ear bones of other vertebrates.

Class Chondrichthyes – sharks and rays

- Endoskeleton made of cartilage- Paired fins- Jaws- 2 chambered heart- Well-developed sense of sight and

smell- Lateral line system (for sensing

pressure changes – vibrations - in water); whole body acts as an “ear”

- unique scales; teeth may be modified scales

- Oviparous, ovoviviparous, and a few are viviparous

- Internal fertilization using claspers to deposit sperm in female reproductive tract

Sharks have a unique digestive structure called spiral valve that increases surface area

Sharks & some rays are carnivores

Rays (and the largest sharks) are suspension feeders

Can detect electrical fields of living organisms with special pores in their skin (not the same as the lateral line system which they also have)

Class Osteichthyes

Tuna, perch, bass, clown fish, eels, seahorses, goldfish, catfish, etc….

* One of the most successful groups on Earth – ever!- Endoskeleton made of bones- Swim bladder- Usually, external fertilization & oviparous (think caviar)- Lateral line system- Scales different from those in sharks - 2 chambered heart (all fish!)- Water balance important; some fish excrete salt through

their gills, others very watery nitrogenous waste using kidneys

Above: internal anatomy of a ray-finned fish

left - photo of a lobe-finned fish; right – photo of a lungfish

Three main groups of Osteichthyes – bony fish

Aquatic tetrapods gave rise to the first amphibians, who probably came on land in search of food (abundant plant and arthropod species in Devonian)

Amphibian VocabularyEctotherm – organism that must gain (or lose) heat from the environment to maintain body temperature; metabolism is NOT sufficient to heat the body; most invertebrates, fish, amphibians, & reptiles

Endotherm – organism that maintains a stable body temperature through metabolism; few reptiles, most birds and mammals, insects

Metamorphosis – change from a sexually immature stage to a sexually mature stage in the life cycle; involves change in body structure and niche; ex) tadpoles are herbivorous, aquatic larvae with gills and no limbs that change into carnivorous, terrestrial adult frogs with lungs and 4 limbs

Tetrapod – vertebrate with 4 limbs located in pectoral and pelvic girdles

Lungs – internal respiratory organs that exchange gases across a membrane surface, usually in conjunction with the circulatory system

Cloaca – common opening to the outside of the body through which fecal material, nitrogenous waste and gametes pass; common to amphibians, reptiles, and birds

Class Amphibia

Frogs, toads, salamanders, and newts- Ectotherms - Need H2O for breeding- Metamorphosis (tadpole frog)- Gas exchange through moist skin & mouth; primitive

balloon-like lungs- External fertilization- Oviparous- 3-chambered heart- Many have chromatophores in the skin for coloration, as

well as poison glands for defense- Nitrogenous waste varies – aquatic habitat – dilute urine;

terrestrial, concentrated urine

3 major groups of amphibians:

Apoda – caecilians; legless

Anura – frogs & toads; tailless

Urodela – salamanders & newts

Reptile VocabularyAmniotic egg – adaptation to terrestrial life that

results in a water-proof egg with extra-embryonic membranes that aid in the vital functions of a

living organism

Extinct – all members of a species have died; ex) pterosaurs

Extant – members of a species are still alive

Bask – behavioral adaptation of ectotherms to increase body heat; involves moving to locations where more radiant energy (such as from the sun or warm rocks) is available for absorption

Amniotic egg in reptiles

- note leathery shell characteristic of reptilian eggs

Class Reptilia turtles, snakes & lizards, crocodiles

- Ectotherms – bask and hide to regulate temperature*- Scaly, waterproof skin- Respire through lungs only**- Internal fertilization- Oviparous, ovoviviparous, viviparous (depending on

species)- 3 or 4 chambered heart- Nitrogenous waste is a paste rather than a liquid for

water conservation; uric acid

- Extinct reptiles include dinosaurs and pterosaurs, which dominated the Earth during the Triassic period

Major extant groups of reptiles:

Squamata – snakes & lizards

• both snakes and lizards shed their skin as they grow

• Loss of legs is unique to snakes within the reptiles; remnants of pelvic girdles present in boas, as are external claws on the abdomen

• many have unique adaptations for life as predators

• Jacobson’s organ – when a snake flicks its tongue it is collecting molecules that are then brought in to Jacobson’s organ for “processing”; kind of a combined sense of taste and smell

• Pits – many snakes have heat sensory organs on their head that gives an IR picture of an organism, decreasing dependency on vision

• Hollow fangs – with or without poison glands for capturing, holding, and killing prey

• Muscles the length of the body allow it to move quickly and many use those muscles for immobilizing and strangling prey

Major extant groups of reptiles: (cont’d)

Testudines – turtles and tortoises

* Some are herbivorous, but most are carnivorous

• Lay eggs on land (oviparous)

• Cloaca is secondary respiratory surface in aquatic species **

• Shell is part of the body, connected to muscle and intimately intertwined with the skeleton

Crocodilia – alligators and crocodiles (caiman, and other related species)• Adapted for aquatic life with upturned nostrils and eyes

on top of head

• endothermic*

• 4-chambered heart

• Related to feathered reptiles

Major extant groups of reptiles: (cont’d)

crocodiles

American alligator

gharial

Bird VocabularyFeather – modified scale used for flight and insulation (contour and down)

Keel – sternum modified for flight muscle attachment

Ratite – flightless birds

Beak – adaptation to the diet of a bird; cranial structure used for feeding and defense

Air sac – pocket attached to the lungs that aid the bird in maintaining constant air flow into the lungs, allowing for flight at high altitudes and greater muscle use

Preen gland - gland located on the base of the tail, especially in aquatic birds, that produces oil for waterproofing the feathers

Crop – portion of esophagus used for temporary storage of food

Gizzard – chamber of the stomach for grinding food

Birds are reptiles

Class AvesBirds

- Endothermic - 4 chambered heart- Internal fertilization- Oviparous- Amniotic eggs with calcerous, hard shells- Cloaca- Nitrogenous waste paste-like for water

conservation; uric acid- Beaks and claws modified for specific niche- Classified as reptiles by many taxonomists- Digestive system modified for diet, including

crop & gizzard

- Many modifications for flight:- Only organism with feathers (modified scales) for

flight and insulation- Evolutionarily may have began as courtship or

defensive displays (behavioral adaptation, rather than for flight)

- Hollow bones - make bird lightweight- Front limbs modified into wings- Air sacs to aid in breathing at high altitudes- Unique muscle tissue for sustained, intense use- Keel – modified breastbone for muscle attachment

Birds migrate – move long distances on a seasonal cycle to reach mating and/or feeding grounds

8600 species of birds in 28 orders• Flightless birds called ratites – emu, ostrich, kiwi

• Penguins have wings modified for swimming

• Aquatic birds have preen gland to keep their feathers from becoming saturated, impeding flight

• Most birds are passeriformes – perching birds, including jays, swallows, sparrows, and warblers (see pp. 790 & 91 in your text for more groups of birds)

Bird courtship and mating behaviors are an evolutionary adaptation unique to each species

Many other groups of birds, including birds of prey, marine birds, seed eaters, woodpeckers, hummingbirds, etc

Mammal VocabularyMammary gland – gland adapted to produce protein and fat rich nutrition for offspring during early development

Hair – keratinous growth for insulation, camouflage, and display; made of same material as reptilian scales and bird feathers

Fat – layer of connective tissue for insulation and padding; energy reserve

Diaphragm – sheet of muscle separating thoracic and abdominal cavities used in respiration

Monotreme – mammal that lays eggs

Marsupial – mammal with young that finish developing in a pouch

Marsupium – pouch in a marsupial

Placental – mammal whose young develop in a uterus attached to a placenta

Uterus – muscular organ that houses the fetus until birth

Placenta – extraembryonic tissues that develop as a connection between the circulatory system of the mother and that of the developing fetus

Dentition – tooth pattern; varies with diet; ex) reptilian dentition is characteristically uniform conical teeth for capturing prey, mammalian dentition varies significantly (carnivores, herbivores, insectivores, baleen, omnivores)

Class MammaliaHumans, bears, pigs, horses, dogs, cats, whales, elephants,

mice, koalas, platypus- Endothermic – hair and layer of fat aid in conserving

heat - Hair – keratinous protein that aids in insulation - Mammary glands – produce milk to feed offspring- Internal fertilization

- 2 species of monotreme; oviparous- Marsupials and placentals are viviparous

- Diaphragm for increased respiration & spongy lungs for increased surface area

- 4-chambered heart- Dentition & jaw structure reflect diet- Inner ear contains 3 bones for improved hearing- Large brain; learn; Extended parental care- Most effective kidney for water conservation; urea

Evolutionary advances in jaw structure, dentition, and inner ear structure from reptile to mammal

3 categories of mammals1. Monotremes

- mammals that lay eggs, have hair, and produce milk with mammary glands

- mother produces milk which is excreted from glands on the abdomen and the babies lap up the milk or suck it off the fur of the mother

Echidna and platypus

Platypus has a cartilaginous bill used to find food on the bottom of a pond or river.

Males have poisonous spurs on their hind feet for defense

Platypi store fat in their beaver-like tails

2. Marsupials

- embryo develops in a uterus with a placenta

Immature fetus is born into a pouch called a marsupium.

Young develop in marsupium, attached to a teat, until much more mature.

All marsupials live in Australia with the exception of the opossum, which can be found in the Americas.

Interesting Evolutionary Note

Marsupials and placentals show parallel evolution

3. Placentals

Placental mammals develop in a uterus attached to a placenta until at a comparably advanced stage of development

Widespread on earth – found in every major biome, including marine, arctic, and tundra.

Many orders of placental mammals. 10 discussed as follows:

Orders of Placental MammalsRodentia- razor sharp teeth (rats, squirrels)Lagomorpha- fused hind leg bones (rabbits)Chiroptera- flying mammals (bats)Carnivora- eat meat (lions, tigers, wolves)Cetacea- Blow holes to breathe (dolphins, whales)Insectivora- eat insects (moles, shrews, hedgehog)Artiodactyla- even # of toes (cows, sheep, goat,

pigs, hippos, camels)Perissodactyla- odd # of toes (horse, zebra, rhino)Proboscidea- trunks (elephants)Primates- opposable thumbs (apes, monkeys,

humans)

Order Primates

Prosimians – lorises, lemurs, tarsiers

Monkeys – New World Old World

Prehensile tails

Apes Humans

Gibbon Orangutan

Gorilla Chimpanzee