Chapter 25: Vertebrate Diversity

1. Chapter 25: Vertebrate Diversity

2. 25.1: Vertebrate Origins • 25.1: Vertebrate Origins • Objectives: Identify and give examples of the three groups of organisms in the phylum Chordata. • Describe the characteristics and origins of vertebrates. • Warm Up: In what obvious way is a snake different from a worm? • Words to Know: Chordate, Notochord, Endoskeleton

3. Phylum Chordata • The phylum Chordata is made of three groups: Urochordata, Cephalochordata, and Vertebrates • Both Urochordates and Cephalochordates are invertebrates. • Urochordates are Tunicates like sea squirts. • Cephalochordates are Lancelets that spend most of their lives buried in the sand. • Vertebrates are large, active animals that have a well-developed brain encased in a hard skull. • ALL Chordates share the same four features at some stage in development: • Notochord – a flexible skeletal support rod embedded in the animal’s back. • Hollow Nerve Cord – runs along the animal’s back. • Pharyngeal Slits – slits through the body wall in the pharynx, where water can enter the mouth and leave the animal through these slits without passing through the entire digestive system. • Tail – extends beyond the anal opening and contain muscles for movement. • Most chordate groups lose some or all of these characteristic in adulthood, but they are present in the embryo. • How are humans similar to sea squirts? How are they different?

4. Phylum Chordata

5. Vertebrate Common Features • Endoskeletons • An Endoskeleton is an internal skeleton built of bone or cartilage. • Vertebrate endoskeletons can be divided into distinct parts. • Braincase – protects the brain. • Vertebrae – a series of short, stiff vertebrae are separated by joints and protect the spinal cord. • Bones – support and protect the body’s soft tissues and provide points for muscle attachment. • Gill Arches – found in fish and some amphibians; help support the gills. • Vertebrate endoskeletons can slowly change size and shape.

6. Vertebrate Common Features • Vertebrate Classes • There are currently 7 classes of vertebrates: • Agnatha – jawless fish including lampreys. • Chondrichthyes – cartilaginous fish that include sharks, rays, and chimeras. • Osteichthyes – bony fish that include ray-finned fish, trout, and goldfish. • Amphibia – first vertebrates adapted to land and include frogs, toads, salamanders, and caecilians. • Reptilia – can retain moisture and live exclusively on land. Include snakes, lizards, crocodiles, alligators and turtles. • Aves – Birds, animals with feathers. • Mammals – animals with fur, mammary glands, and three middle ear bones. Includes humans, elephants, kangaroos etc… • How does growth differ between an animals with an endoskeleton and an animal with an exoskeleton?

7. Vertebrate Classes

8. Origins of Vertebrates • Much of what we know comes from fossil evidence found in the Burgess Shale locates in the Canadian Rocky Mountains in the early 1900’s. • Many are dated around the Cambrian explosion.

9. Closest Relatives • Tunicates may actually be the closest relatives of vertebrates. • Scientists have found that tunicates have cells that resemble the neural crest that is also found in vertebrates.

10. Early Vertebrates • The first recognizable vertebrates were fish. • The oldest fish fossils date back 530 million years. • Early fish were small, jawless bottom-feeders.

11. Lampreys • There are more than 35 species of Lampreys. • They are highly specialized fish parasites. • Physical Characteristics include: • Long and slender body plans with NO paired fins. • Mouths surrounded by large suckers. • Tongues covered by tooth-like projections. • The accidental introduction of sea lampreys into the Great Lakes in the early 1900’s had a devastating effect on the fishing industry.

12. Hagfish • A jawless eel-like animal with a partials skull but NO vertebrae. • It uses a notochord for support. • How have scientists’ views on the origins of vertebrates changed?

13. 25.2: Fish Diversity • 25.2: Fish Diversity • Objectives: Identify the characteristics of the two classes of jawed fishes. • Describe the evolution and advantage of jaws. • Warm Up: If you dive into a cold lake without scuba gear or a wetsuit, and you remain underwater and motionless for a few moments, what problems will you have? • Words to Know: Gill, Countercurrent Flow, Lateral Line, Operculum

14. Fish • Fish use specialized organs called gills to take in the oxygen dissolved in water. • Gills are large sheets of thin frilly tissue filled with capillaries that take in dissolved oxygen from the water and release carbon dioxide. • Fish circulatory systems pump blood in a single circulatory loop through a heart with two main chambers.

15. Countercurrent Flow • Countercurrent Flow is the opposite movement of water against the flow of blood in the fish’s gills. • Countercurrent flow maximizes the amount of oxygen the fish can pull from the water by diffusion.

16. Swimming and Maneuvering • Most fish swim by contracting large segmented muscles on either side of their vertebral column from the head to the tail. • Fins help keep fish stable. • What is the connection between countercurrent flow and a fish’s movement in the water?

17. Jaws • Jaws evolved from gill arches. • Gill arches are structures made of bone or cartilage that function as a support for fish’s fills. • Jaws developed from gill arches near the mouth, which fused to the cranium. • Jaws gave vertebrates a huge advantage as predators and quickly pushed them to the top of the food chain. • What advantages are provided to an animal that has jaws, compared with an animal that does not have jaws?

18. Two Groups of Jawed Fish • Jawed fish diversified very quickly after their first appearance about 440 million years ago. • Four groups appeared at this time: • Acanthodians – were fish covered with spines and became extinct 250 million years ago. • Placoderms – were heavily armored with huge bony plates and became extinct 350 million years ago. • Cartilaginous Fish – Skeletons are made of cartilage and include sharks, rays and chimera. • Bony Fish – Include all other living fish

19. Cartilagenous Fish (Chondrichthyes) • Have skeletons made of cartilage. • Their cartilage contains calcium deposits that make it stiffer than the squishy stuff around human joints. • Chimeras are a small group of deep-sea fish with plate-like grinding teeth that feed on crustaceans. • There are more than 300 species of shards and nearly 400 species of rays and skates. • All are predators. • Cartilaginous fish have internal fertilization and many give birth to live young. • They are also powerful simmers with good eyesight and an excellent sense of smell. • All fish have a Lateral Line system, which is a series of shallow canals on the sides of the fish made up of cells that are sensitive to small changes in water movement. • This give fish a sense of “distant touch” letting them sense movement in the water far away.

20. Bony Fish (Osteichthyes) • All other living fish have skeletons made of bone. • There are more than 20,000 species of bony fish living in almost all aquatic environments. • The gills of all bony fish are in a chamber covered by a protective plate called the operculum. • This helps fish move water over their gills. • What is the difference between cartilaginous and bony fish?

21. 25.3: A Closer Look at Bony Fish • 25.3: A Closer Look at Bony Fish • Objectives: Differentiate between the fins of ray-finned fish and lobe-finned fish. • Describe the diversity of body plans of bony fish. • Explain the origin and function of a fish’s swim bladder. • Warm Up: Write common names of fish. Which of those are bony fish? • Words to Know: Ray-fin, Swim Bladder, Lobe-fin

22. Ray-finned Fish • All ray-finned fish, such as goldfish and tuna, have fins supported by a fan shaped array of bones called a ray-fin. • Ray-finned fish can quickly change a fin’s shape, making it easier for the fish to maneuver in the water.

23. Diversity of Body Plans • Long torpedo-shaped fish, such as barracuda are ambush predators. • Fish that are flattened from side to side, like butterfly fish, are great at maneuvering through corals. • Fish that feed on the surface of the water have flattened heads and mouths that point up. • Flatfish are flat-shaped and lie on the sea floor waiting for their prey to swim by. • Some slow-swimming fish use camouflage to hide from predators or prey.

24. Staying Afloat • Most ray-finned fish have lungs modified into a buoyancy organ called a Swim Bladder. • The Swim Bladder, helps a fish float higher or lower in the water, by increasing and decreasing oxygen levels. • What is a swim bladder and how does it work?

25. Lobe-Finned Fish • The lob-finned fish include the ancestors of all terrestrial vertebrates. • Most species are extinct. • Lobe-fins are paired pectoral and pelvic fins that are round in shape. • These fins are arranged around a branching series of bony struts, like the limbs of a land vertebrate.

26. Coelacanths • Are distinctive-looking fish with thick, fleshy fins and a tail with three lobes. • They breathe with gills.

27. Lungfish • Live in streams and swamps in Australia, South America, and Africa. • They can breathe with either gills or lungs. • How are lobe-fins related to vertebrae evolution?

28. 25.4: Amphibians • 25.4: Amphibians • Objectives: Describe the adaptations of amphibians that help them live on land. • Summarize the reproduction and development of amphibians. • Distinguish among the three groups of modern amphibians. • Warm Up: Of the following animals, which are amphibians: frog, turtle, snake, alligator, toad, salamander, iguana? • Words to Know: Tetrapod, Amphibian, Tadpole

29. Amphibians • One of the oldest known fossils of a four-limbed vertebrate was found in 360 million-year-old rocks from Greenland. • All of the vertebrates that live on land, as well as their descendants that have returned to aquatic environments, are Tetrapods. • A Tetrapod is a vertebrate that has four limbs. • Amphibians are animals that can live BOTH on land and in water. • Amphibian literally means “life on both sides”. • Depending on the species, amphibians breathe through their skin or with the use of gills or lungs. • Amphibians have a three-chambered heart. • What adaptations helped amphibians move from water to live on land?

30. Amphibian Reproduction • Amphibians need a source of water to reproduce. • Amphibians have several ways to stop eggs from drying out that include: • Laying eggs directly in water, • Laying eggs on moist ground. • Wrapping eggs in leaves. • Brooding eggs in pockets on the female’s back. • Some frogs start off as Tadpoles – aquatic larvae that have gills and a broad-finned tail.

31. Amphibian Metamorphosis • To grow into terrestrial adults, tadpoles must undergo metamorphosis. • Eggs hatch to release tadpoles. • As the tadpole matures, the gills are reabsorbed and lungs develop. • The circulatory system is reorganized to send blood to the lungs. • The tail fin is reabsorbed. • The body grows limbs and completely reorganizes its skeleton, muscles, and parts of the nervous system. • Many Amphibians do NOT undergo metamorphosis and develop directly into their terrestrial forms. • Describe the stages of amphibian metamorphosis.

32. Three Groups of Amphibians • Salamanders • There are more than 300 species of salamanders. • They have a long body, four walking limbs, and a tail. • They walk with a side-t-side movement. • They are carnivores.

33. Three Groups of Amphibians • Frogs and Toads • There are over 3000 species of frogs. • Toads are a family of frogs that have rougher and bumpier skin and are poor jumpers. • Frogs and toads can make toxins that protect them from predators.

34. Three Groups of Amphibians • Caecilians • Are legless, burrowing amphibians that live in the tropics. • There are 160 species ranging in length from about 10 cm to 1.5 meters. • Have banded bodies that make them look like earthworms. • How are caecilians different from other amphibians?

35. 25.5: Vertebrates on Land • Objectives: Describe two important characteristics of amniotes that help them retain water. • Explain the evolutionary importance of the amniotic egg. • Warm Up: Why is the amniotic egg so significant to life on land? • Words to Know: Amniote, Keratin, Amniotic Egg, Placenta

36. Amniotes • An Amniote is a vertebrate that has a thin, though, membranous sac that encloses the embryo or fetus. • Amniotes first appeared as small lizard-like creature in the late Carboniferous period. • All Amniotes share a set of characteristics that prevent water loss. • Skin cells are waterproof with Keratin – a protein that binds to lipids inside the cell forming a hydrophobic layer that keep water inside the animal from reaching the skin. • Kidneys and large intestines are bigger in amniotes than in amphibians, because they can reabsorb water. • What makes your skin cells waterproof? Why is this important?

37. Reproduction Without Water • The Amniotic Egg is an almost completely waterproof container that keeps the embryo from drying out as it develops. • Once the amniotic egg evolved, vertebrates no longer had to go back to water for reproduction. • Most Mammal embryos develop inside of the mother’s reproductive tract. • The Placenta is a membranous organ that develops in female mammals during pregnancy. • It carries nutrients from mother to embryo. • How is an amniotic egg protected from water loss?