Vertebrate Animals

Vertebrate Animals DOMAIN- Eukarya KINGDOM- Animalia • PHYLUM- Chordata • SUBPHYLUM- Vertebrata • CLASS- 7 different • ORDERS- 10 Placental mammals

Phylum Chordata • Recall that vertebrates are chordates. • Phylum Chordata includes the lancelets and tunicates (invertebrate chordates) as well as the vertebrates • All chordates have:

Notochord • flexible rod-like structure • main longitudinal structural element of chordates and of the early embryo of vertebrates • plays an organizational role in nervous system development • becomes part of the vertebral column.

Pharyngeal slits Gill-like slits on vertebrates in embryo stage Disappear in most adults Continue on in some vertebrates

Characteristics of all Vertebrates • Endoskeleton with a backbone for support of a dorsal nerve cord & muscle attachment • Distinct skull/cephalization (head) • Bilateral symmetry (like us!) • 2 pairs of jointed appendages • Coelom(cavity within between middle and inner tissue layer) • 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 – semiaquatictetrapods with split lives & 3-chambered hearts • Anura – “tailless ones” – frogs & toads • Urodela – “tailed ones” – salamanders & newts • Apoda – “legless ones” - caecilians • Reptiles – terrestrial amniotetetrapods with scales & lungs & 3-ish to 4 chambered hearts • Squamata – lizards and snakes • Testudines – turtles & tortoises • Crocodilia – alligators, crocodiles, and related species

Birds – terrestrial amniotetetrapods 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 amniotetetrapods 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 Agnatha Hagfish 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 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) Sharks & some rays are carnivores Rays (and the largest sharks) are suspension feeders

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

Three main groups of Osteichthyes – bony fish Above: internal anatomy of a ray-finned fish left - photo of a lobe-finned fish; right – photo of a lungfish

Summing up FISH FEEDING – herbivores, carnivores, filter feeders, etc. RESPIRATION – Most have gills that absorb oxygen by diffusion from water to blood. A few also have lungs. CIRCULATION – two-chambered heart that pumps blood in loop around body.

EXCRETION – Kidneys expel waste as ammonia. Salt water fish must retain water that leaks out of them, so they have very concentrated urine. Fresh water fish have water leak into them, so must constantly expel very d________ urine. Solid waste is expelled from stomach.

SENSES AND RESPONSE – brain at end of spine. Very good senses of sight smell pressure/movement (lateral line) hearing less good Pain? Evidence is inconclusive…

MOVEMENT– muscles move fins Scales reduce resistance swim bladder filled with air/gas to adjust buoyancy REPRODUCTION – most have external fertilization. Eggs hatch outside body (oviparous) Some fertilize eggs in body and keep eggs until hatched inside (ovoviviparous) Sharks etc. viviparous embryo gets nourishment from mother.

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 Vocabulary Ectotherm – 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: live in water and on land, breathe with lungs and through skin, moist skin, no scales

More… Frogs, toads, salamanders, and newts • Ectotherms • Need H2O for breeding • Metamorphosis (tadpole  frog) • Gas exchange through moist skin & mouth; primitive balloon-like lungs • Goos eyes, tympanic membrane • 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: Anura – frogs & toads; tailless Apoda – caecilians; legless Urodela – salamanders & newts

Summing up AMPHIBIANS FEEDING – tadpoles filter feeders/herbivores. Adults carnivores. Many have long sticky tongues RESPIRATION – tadpoles through skin and gills, adults have lungs and breathe through skin CIRCULATION – three-chambered heart that pumps blood in double loop around body.

EXCRETION – Kidneys expel waste through cloaca. Solid waste is expelled from stomach. SENSES AND RESPONSE – brain at end of spine. Very good senses of sight (big eyes, covered with nictitating membrane to protect eye.) hearing (tympanic membrane behind eye acts as ear)

MOVEMENT– tadpoles swim like fish Frogs strong hind legs to jump. Salamanders walk or run. REPRODUCTION – external fertilization. Eggs hatch outside body (oviparous) in water.

REPTILES • Terrestrial • Well-developed lungs • Dry scales and waterproof skin, amniotic eggs with shells allow for living on land without drying out • Control body temperature by moving into/out of sunlight

Reptile Vocabulary Amniotic 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

Major extant groups of reptiles: (cont’d) gharial crocodiles • 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 American alligator

Summing up REPTILES FEEDING – Some lizards and turtles are herbivores; snakes and crocodiles are carnivores http://www.youtube.com/watch?v=p-nj_iOBDqA RESPIRATION – well-developed lungs CIRCULATION – double loop blood flow to heart with two atria and one or two ventricles

EXCRETION – Kidneys expel waste as ammonia through cloaca. Solid waste is expelled from stomach. SENSES AND RESPONSE – brain at end of spine. Very good senses of sight smell taste – tongue and organ in mouth sense vibrations with skull body heat – rattle snakes

MOVEMENT– Strong legs and body muscles allow rapid movement REPRODUCTION – eggs laid on land after internal fertilization; leathery, waterproof shell Males have penises (snakes have two) that penetrate female body.

BIRDS – flying reptiles?

Bird Vocabulary Feather – 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

Class Aves Birds • 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

Vertebrate Animals