Kingdom Animalia Phylum Chordata

Kingdom AnimaliaPhylum Chordata The vertebrates and their relatives

Phylum Chordata • Characteristics of a chordate • A dorsal hollow nerve cord (spinal cord in vertebrates) • A notochord (most vertebrates only have a notochord during development – becomes the backbone in vertebrates) • Pharyngeal Pouches (develop into gills in fish and amphibians) • Muscular Tail (disappears in humans)

Subphylum Urochordata • Tunicates (also known as “sea squirts”) • Look similar to other chordates during development, but completely different as adults

Subphylum Cephalochordata • Lancelets: live in the ocean with their body buried in sand • Have a definite mouth and no jaws • Long pharynx with up to 100 gill slits • Breathe through their body surface • Have a simple digestive system, heart, and closed circulation • Use paired muscles to move

Subphylum Vertebrata • 99% of chordates are vertebrates • Fish 24,000 species • Amphibian 4,000 species • Reptiles 6,000 species • Birds 10,000 species • Mammals 4,500 species

Fishes • Aquatic vertebrates characterized by: • Fins (Movement) • Scales (Protection) • Gills (Breathing) • There are fish with exceptions! • Can you name any?

Fish Evolution • Fish were the first vertebrate to evolve • Evolved about 540 mya • Were jawless and covered in armored plates • Devonian Period = Age of the Fishes • Fish developed both jaws and fins at this time

Body Systems of Fishes • Fish feed in a variety of ways including parasites, carnivores, herbivores, etc. • Most fish breathe using gills • Gills are feathery filaments containing a network of capillaries to increase surface area for CO2 and O2 exchange • Fish have closed circulation

Body Systems of Fishes • Fish digestive systems are similar to that of humans • Ammonia is excreted by diffusion of water through gills and by use of kidneys • Salt water fish conserve bodily fluids by having concentrated urine • Fresh water fish have dilute urine • Fish that move from fresh to salt water alter their kidney function to adapt to tonicity!

Fish Senses • Fish exhibit cephalization • Many fish have Chemoreceptors for an extraordinary sense of taste and smell • Lateral Line System – allows fish to sense movement and vibration

Fish Senses • Swim Bladder – adjust buoyancy • How does pulling a fish from 40 feet of water affect the size of its swim bladder?

Fish Reproduction • Oviparous – egg laying; includes both internal (some sharks) and external (most fishes) fertilization • Ovoviviparous – eggs develop inside mother’s body and are nourished by egg yolk; young are born alive • Viviparous – the mother’s body nourishes the developing young which are born alive

Groups of Fishes • Class Cephalospidomorphi – lamprey • Class Myxini – hagfishes • Class Chondrichthyes – cartilaginousfishes • Class Osteichthyes – bonyfishes

Lamprey and Hagfishes • Are jawless fishes • Have mouths of soft tissue and no true teeth • Have no bones • Are the only vertebrates that do not have vertebral columns as adults

Lamprey • Are filter feeders as larvae and parasites that suck blood and tissues of fish as adults

Hagfishes • Feed on dead and dying fish using a toothed tongue to scrape a hole in the fishes side • Secrete large amounts of slime • Have 6 hearts and an open circulatory system

Cartilaginous Fishes • Includes sharks, rays, skates, sawfishes, and chimaeras • “Chondros” = Greek word for cartilage • A typical shark has 3000 teeth arranged in 6 to 20 rows • Not all are carnivores, the largest sharks are filter feeders • Some have flat teeth for crushing mollusks and crustaceans

Bony Fishes • Skeletons are made of calcified bone • Includes fish we are most familiar with: Sunfish, Muskellunge, Northern Pike, Walleye, Smallmouth Bass, etc.

Fish Ecology • Some fish can live in both salt water and fresh water • Anadromous Fishes – spend most of their life in the ocean but move to fresh water to breed • Catadramous Fishes – spend most of their life in fresh water but move to the ocean to breed

Class Amphibia • Amphibians gave rise to all other land vertebrates • Amphibian means “double life” • As larvae they are typically aquatic filter feeders or herbivores breathing through gills • As adults most species are terrestrial carnivores that breathe through their moist skin and have lungs

Adaptations to Life on Land • As the amphibians developed in the late Devonian Period 360 mya they needed to adapt to terrestrial life • Keep from drying out • Breathe using lungs, not gills • Bones in limbs allow movement • Ribs to support and protect internal organs • Amphibians dominated the Carboniferous Period 345 to 285 mya

Amphibian Body Systems • Amphibians have a well developed digestive system similar to that of humans • As most amphibians develop lungs as adults, some are lung-less and only breathe through their skin • They have closed circulation and a 3 chambered heart with a double loop system similar to that of a human • Ammonia is disposed of in urine through the use of kidneys

Amphibian Reproduction • Most amphibians lay their eggs in water; fertilization is external • Some salamanders fertilize internally

Amphibian Reproduction • In most cases of external fertilization, the male will attach itself to the female. Eggs and sperm are released simultaneously and encapsulated in a jelly that attaches to aquatic plants. • The jelly nourishes the developing embryos • Tadpoles hatch and metamorphose into adults

Amphibian Reproduction • Most amphibians abandon their eggs once they lay them. • Some care for both eggs and young • Some incubate their eggs in unusual places: in their mouth, on their back, or in their stomach

Amphibian Senses • Amphibians have a well developed brain and spinal cord similar to that of a fish • Eye’s are protected by a nictitating membrane • A tympanic membrane, or eardrum, is located on either side of the head • Many have a lateral line system similar to that of a fish

Groups of Amphibians • Order Urodela: Salamanders and Newts • Order Anura: Frogs and Toads • Order Apoda: Caecilians

Salamanders and Newts • Have long bodies and tails • Both adults and larvae are carnivores • Most adults are terrestrial and live in damp forests • Some salamanders, such as mud puppies, keep their gills and live in water all their lives

Frogs and Toads • Have the ability to jump • Frogs have longer legs and can jump farther than toads • Frogs are closely tied to water; toads are more terrestrial

Caecilians • Least known of the amphibians • Are legless and burrow in moist soil or sediment • Feed on small invertebrates such as termites • Some have scales

Amphibian Ecology • Most are a great meal for birds and reptiles • Some have toxins to poison predators • Some have bright colors to warn of their toxins • Some mimic the bright colors of others and are harmless

Amphibian Ecology • Amphibian populations are declining worldwide due to several factors: • Global Warming • Decreasing Habitat • Depletion of the Ozone • Water Pollution • Introduced Aquatic Predators • Fungal Infections • Increasing human population!

Class Reptilia • Land vertebrates with a well developed skull, a backbone and tail, and four limbs • Exemptions: snakes have no legs, and turtles have a shell formed of fused vertebrae? • Can a turtle lose its shell?

Reptile Evolution • The oldest reptile fossils date back to the early Carboniferous Period some 350 million years ago • Dinosaurs of the Triassic and Jurassic Period ruled the earth until 65 million years ago

Reptile Body Systems • Reptiles are ectotherms – rely on interactions with the environment to control their body temperature • Reptiles have well developed lungs, four chambered hearts, and a well developed brain and spinal cord • Reptiles’ legs are rotated farther under their body than amphibians allowing them to carry weight and walk on land more efficiently

Reptile Reproduction • Internal Fertilization – males have a penis to place sperm in the female’s cloaca • Most are oviparous • Turtles leave their nests unattended while alligators protect their nest • Some snakes are ovoviviparous

Reptilian Eggs • Reptiles have amniotic eggs – named after one of the four membranes around the developing embryo • Amnion: produces watery environment around embryo • Yolk Sac: contains nutrient rich yolk that feeds embryo • Chorion: allows gas exchange • Allantois: stores waste

Groups of Reptiles • Order Squamata: lizards and snakes • Order Crocodilia: alligators, crocodiles, caimans, and gavials • Order Chelonia: turtles, tortoises, terrapins • Order Rhynchocephalia - tuataras

Lizards and Snakes • Most lizards have legs, clawed toes, external ears, and movable eyelids • Some lizards do not have legs and look more like a snake

Alligators, Crocodiles, and their Relatives • Long broad snout and squat appearance • Fierce carnivores • Very protective of their nests • Alligators and Caimans live only in fresh water and almost exclusively in North and South America • Crocodiles live in both fresh and salt water and are native to Africa, India, and Southeast Asia

Turtles, Tortoises, and Terrapins • Turtles – live in or near water • Tortoises – are terrestrial • Terrapins – live in brackish water • Carapace: Dorsal side of Shell • Plastron: Ventral side of Shell

Tuataras • Tuataras are the only living member of the Order Rhynchocephalia • Beak headed reptiles that live on a few small islands off the coast of New Zealand • Differ from lizards as they lack external ears and retain primitive scales • They have a legendary “third eye” which is part of a complex organs on top of the brain – the function is unknown

Ecology of Reptiles • Many are in danger due to loss of habitat • Humans also hunt them for food, pets, and their skins (for bags and boots) • Many conservation efforts are underway, but more are needed worldwide

Class Aves • Characteristics of most birds • Maintain a constant internal body temperature • Covered in feathers • Have two legs for walking and perching • Front limbs are wings • Most are adapted for flight

Feathers • Used for flight and warmth; several types • Contour Feathers: provide the lifting force and balance needed for flight • Down Feathers: trap air close to the body and keep the bird warm • Powder Down: found on ducks and other birds that live on or in water; release a fine powder that repels water

Evolution of Birds • Oldest known fossil is Archaeopteryx which lived during the Jurassic Period 150 mya. • Had teeth in its beak, a jointed tail, and toes and claws on its wings • Birds are very closely related to dinosaurs, but scientists disagree on whether birds evolved from dinosaurs – or- birds and dinosaurs evolved from one common ancestor

Body Systems of Birds • Endotherms: can generate their own body heat; warm-blooded • Smaller birds must eat more in relation to its size due to Surface Area to Volume Ratio

Feeding habits of Birds • They lack teeth and therefore do not chew • Beaks are adapted to the types of food they eat • Bird Digestion • Crop: enlargement of the esophagus used to store food • Gizzard: has muscular walls and small bits of gravel used to grind food

Respiration • Birds have very efficient lungs that provide oxygen rich blood during both inhalation and exhalation • Inhaled air enters posterior and anterior air sacs it then travels through the lungs and is exhaled • Therefore the air flows into the air sacs and out of the lungs in one single direction, always providing oxygen rich air

Circulation and Excretion • Two loop circulatory system, similar to that of humans • Ammonia is removed by the kidneys, converted to high concentration uric acid and defecated (bird droppings); similar to reptiles

Kingdom Animalia Phylum Chordata