Kindom Animalia, Phylum Chordata pgs 448- 479 R. Pushie CHS 2011

What characteristics set chordates apart from other phyla? At some point in their development all chordates have these 4 structural characteristics: A notochord – becomes the vertebral column in humans A muscular pharynx with gill slits A post-anal tail – the coccyx in humans A hollow dorsal nerve chord – later modified into a brain and spinal cord These attributes are always found in the larval forms or early embryo, although they may be absent in the adult.

Phylum Chordata is divided into three subphyla Subphylum Urochordata Example: tinucates Subphylum Cephalochordata Example: Lancelets Subphylum Vertebrata Examples: fish, amphibians, reptiles, birds, mammals

Subphylum Urochordata & Subphylum Cephalochordata Represent 5% of chordates Aquatic animals that possess the 4 characteristics of chordates. No backbone or vertebral column Perhaps represent a transient step between invertebrates and vertebrates

Subphyum Vertebrata 95% of all chordates All possess vertebrae, which are hollow cartilaginous or bony structures that surround the dorsal nerve cord. Body plan includes (pg 449): Endoskeleton Large brain with a protective skull Advanced nervous system Complex heart and circulatory system Special outer body cover One to two pairs of appendages Large coelom

Subphylum Vetebrata Terminology Endotherm – warm blooded animals. Internal temperature remains constant regardless of environment. Ex: mammals and birds. Ectotherms – cold blooded animals. Body temperature and metabolic rate change with the surroundings. Ex: all other vertebrates including fish, frogs, snakes etc.

12.2 Fish pg 452 Divided into 3 groups: Organ/Structure Function Jawless –Class Agnatha. Ex: lampreys, hagfish Cartilaginous – Class Chondrictheys. Ex: Sharks, skates, rays Bony fish - Class Osteichthyes. Ex: Salmon, trout, tuna. Organ/Structure Function Heart 2 chambered heart. Circulatory System Blood vessels circulate oxygenated blood Respiration Blood travel to Gills to be oxygenated Nervous System Brain, spinal cord and peripheral nervous system. Reproduction Separate sexes. Internal and external fertilization. Digestion One way, developed system.

Fish Circulatory System

Lobe-finned fish Amphibians Lobe-finned fish, have a fleshy lobe at the base of their fins that is leg-like in appearance. Scientists believe that this fish is the ancestor of amphibians! Amphibians first appeared 350 million years ago. *Figure 6, pg 454 Lobe-finned fish, were thought to be extinct until 1938, when a coelacanth Latimeria was first captured by chance, they were known only from the fossil record. Since then several dozen have been captured and some of their behavior has been filmed using robotic cameras. Latimeria is important because it provides an opportunity to compare observations from the fossil record with a living animal.

12.3 Amphibians pg 455 Reproduction external fertilization which only occurs in aquatic environments. Gas exchange Young amphibians use gills as they live in aquatic environments. Adult amphibians perform gas exchange through moist skin, (cutaneous respiration), and poorly developed lungs with little internal folding and a small surface area as they are mostly terrestrial. Nervous and Digestion Systems – highly developed nervous and digestive systems.

12.3 Amphibians pg 455 Circulatory System – Inefficient 3 chambered heart where oxygenated blood and deoxygenated blood are mixed and then pumped to the body.

12.4 Reptiles pg 457 Reptiles are the first fully terrestrial animals. Reptiles first appeared 350 million years ago. 3 subclasses: Anapsida – turtles, tortoises Lepidosaura – lizards, snakes, tuatara Archosaura – crocodiles, aligators and dinosaurs Body plan includes: Thick skin with protective with surface scales to prevent water loss (gas exchange) Highly developed lungs with much internal folding More developed 3 chambered heart The amniotic egg Lightweight skeleton Different joint positions allowing for more efficient movement

12.4 Reptiles pg 457

12.5 Birds pg 461 Class Aves Characteristics of birds: Descendant of reptiles, similarities retained include skull structure, and presence of scales on beak, legs and feet. The first endotherms Only animal with feathers (evolved from reptilian scales) Their anterior limbs are modified as wings for flight, while the posterior pair is adapted for walking, swimming, or perching.

12.5 Birds pg 461 Class Aves Characteristics for Flight Circulatory System –4 chambered heart. No mixing of oxygenated and deoxygenated blood. Respiratory System – Highly developed lungs and the presence of air sacs which provide continuous oxygen as well as buoyancy. Limbs – lighter, hollow bones. Excretion – purely semi solid, no urinary bladder Digestion – rapid and efficient Senses – excellent hearing and acute colour vision. Superior sight during the day and night.

12.6 Mammals pg 465 Monotremes: mammals that reproduce by laying eggs. Descendant of a different reptilian ancestor than other mammals. Example – duck billed platypus. Marsupials: mammals that give birth to partially developed embryo that continue further development in the mother’s pouch. Example – kangaroos, wallabies, and koalas Placental Mammals: a type of mammal that has all of the embryo development within the uterus of the female. Includes 95% of all mammals. Example – humans, dogs, horses etc

12.6 Mammals pg 465 Mammalian Characteristics include: Hair Sweat glands Teeth Fleshy lips A diaphragm A four chambered heart A middle ear Mammary glands that produce milk (females) Endoskeleton A complex brain and nervous system

4 chambered heart

Application Questions Phylum Chordata Read pgs 446-450, do questions pg 449, questions #1, 4, pg 452 #3, 4 Class Fish Read pgs 452-455, do questions pg 454, questions #1, 5, pg 455 #4, Class Amphibian Read pgs 455-457, do questions pg 460, questions #1, 2

Application Questions Class Reptilia Read pgs 457-461, do questions pg 460, questions #3, pg 461 #2,4,5 Class Aves Read pgs 461-465, do questions pg 465, questions #1, 2 Class Mammalia Read pgs 465-478, do questions pg 478, questions #6, pg 481 # 5, 7, 9