Vertebrates (5% of Animal Kingdom) The Phylum Chordata is the phylum of vertebrates.
Phylum Chordata(Chordates) • Most members of this phylum are vertebrates with bony skeletons and backbones. • Most common on land & in water. • Many fewer chordate species than invertebrate species.
Chordate Characteristics At some stage in their life cycle, Chordates have: • A dorsal nerve cord(nerves branch to all parts of the body) • A notocord(rod of cartilage that runs along the dorsal length of the body) • Gill slitsin the pharynx (throat).
An Exception There are two groups of invertebrate animals that are part of the Phylum Chordata. • Tunicates • Lancelets They have the three characteristics of chordates.
Comparing Vertebrate Chordates The organisms within the Phylum Chordata are divided commonly by: 1. The presence of an amnion (fluid-filled sac around the embryo). 2. The development of the lung.
Chordate Respiration • Fish are the only vertebrates adapted to live their lives entirely in water. They obtain oxygen from the water through their gills. • Reptiles, birds & mammals have lung-base respiratory systems.
Chordate Circulation There are three types of circulatory pathways among vertebrates. • Mammals, birds, crocodiles • Amphibians & most reptiles • Fishes *** See and know Figure 6.25 on page 193.
Chordate Reproduction There are two main methods of fertilization in vertebrates: • External • Internal
External Fertilization • The egg & sperm meet outside the body. • Ex. Sharks, frogs
Internal Fertilization • The egg & sperm meet inside the body • Ex. Reptiles, birds, mammals • Mammals are the only vertebrates in which the embryo develops internally! (Exceptions: Duckbill Platypus & Kangaroo)
Phylum Chordata Four Subphyla: • Urochordata (tunicates) • Cephalochordata (lancelets) • Agnatha (jawless fish, i.e. hagfish) • Gnathostomata (jawed chordates)
Subphylum Gnathostomata(jawed chordates) • Divided into 6 classes: • Chondrichthyes (cartilaginous fish, i.e. sharks) • Osteichthyes (bony fish) • Amphibia (amphibians) • Reptilia (reptiles) • Aves (birds) • Mammalia (mammals) *** You should know the class (Table 6.3, page 190)
1. Chondrichthyes(Cartilaginous Fish) • Skeleton is made of cartilage instead of bone • Have 5-7 gill slits but lack gill covers • Ex. Rays, skates, sharks
2. Osteichthyes(Bony Fish) • Most numerous of the vertebrates. • Skeletons are made of bone. • Ex. Herring, trout, cod
3. Amphibia(Amphibians) • In early stages are gill breathers in water, but live as air breathing adults on land. • Have a heart with 3 chambers. • Ex. Frogs, toads
4. Reptilia(Reptiles) • Have better developed lungs than amphibians. • Have a rib cage • Skin is thick and scaly & is made from keratin (a protein) • They shed their skin several times each year. • Ex. Lizards & snakes
5. Aves(Birds) • Have feathers • Bones are hallow…..why?? • Ex. Robins, Blue Jays, Swallows
6. Mammalia(Mammals) • Have hair • Have milk-producing mammary glands • Give birth to live young • Most live on land • A small number are adapted to life in the water (i.e. whales, dolphins)
One Short Video • Phylum Chordata “How Stuff Works”
Section 6.3Review Questions • Do question #’s 1-6 on page 196. • Do “A Vertebrate Survey” Worksheet.
Section 6.3 Answers • On what basis do biologists distinguish animals from members of other kingdoms? They use characteristics such as: reproduction motility digestion cell type body form
Why is Phylum Arthropoda considered the most successful animal phylum? Arthropods have an exoskeleton, segmentation, a nervous system, and nutrition-related adaptations that have all helped them to be successful.
What characteristics distinguish chordates from other animals? Unlike other animals, chordates have a notochord.
How is the body of a flatworm similar to and different from the body of a sponge and a cnidarian? They are all multicellular. The flatworm has bilateral symmetry, and the sponge is asymmetrical while the cnidarian is radial. The flatworm has a simple nervous system like cnidarian but sponges do not have tissues or organs. All three lack a body cavity.
Sketch a diagram illustrating the difference between radial symmetry and bilateral symmetry in animal bodies. Ex. A starfish vs. a lobster
Construct a simple key that enables you to differentiate among any four animal phyla. Answers will vary!! Chordata = dorsal nerve cord Arthropoda = jointed appendages Platyhelminthes = three tissue layers Cnidaria = two tissue layers