Albia Dugger Miami Dade College Cecie Starr Christine Evers Lisa Starr Chapter 24 Animals II: The Chordates (Sections )

24.1 Windows on the Past Fossils are physical evidence of changes that led to modern animal diversity Radiometric dating assigns fossils to places in time Structure, biochemistry, and genetic makeup of living organisms provide information about branchings

Transition Fossils Fossils reveal that birds evolved from feathered dinosaurs, and that some early birds had a bony tail and teeth

24.2 The Chordate Heritage Chordates are distinguished by their embryonic traits Chordates include vertebrates and two lineages of marine invertebrates chordate Animal with an embryo that has a notochord, dorsal nerve cord, pharyngeal gill slits, and a tail that extends beyond the anus

Chordate Characteristics Four features define chordate embryos: a notochord a dorsal hollow nerve cord a pharynx with gill slits a muscular tail extending past the anus These features may or may not persist in adults

Key Terms notochord A rod of stiff but flexible connective tissue that runs the length of the body in chordate larvae or embryos and supports it

Invertebrate Chordates Invertebrate chordates include lancelets and tunicates lancelet Invertebrate chordate that has a fishlike shape and retains the defining chordate traits into adulthood tunicate Invertebrate chordate that loses its defining chordate traits during the transition to adulthood

Lancelets Gill slits filter food particles out of the water and also function in gas exchange

Fig 24.1a, p. 378 Lancelets

Fig 24.1a, p. 378 anus tail extends past anus eyespot notochord dorsal nerve cord pharynx with gill slits Lancelets

Fig 24.1b, p. 378 Lancelets

ANIMATION: Lancelet body plan To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

Tunicates Larvae swim about briefly, then undergo metamorphosis Adults retain only the pharynx with gill slits Adults feed by drawing water in through an oral opening, past gill slits, then expels it through a second opening

Larval and Adult Tunicates.

Fig 24.2, p. 378 pharynx with gill slits A C 1 cm Larval and Adult Tunicates

Fig 24.2a, p. 378 Larval and Adult Tunicates

Fig 24.2c, p. 378 Larval and Adult Tunicates

ANIMATION: Tunicate body plan To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

Overview of Chordate Evolution Craniates are chordates with a braincase of cartilage or bone Most craniates are vertebrates craniate Chordate with a braincase vertebrate Animal with a backbone

Chordate Evolution (cont.) Vertebrae and other skeletal elements are components of the vertebrate endoskeleton Jaws evolved from bony parts that supported gill slits of early jawless fishes endoskeleton Internal skeleton made up of hardened components such as bones

Chordate Evolution (cont.) Evolutionary modifications allowed animals to move from water onto land: Fins would evolved into limbs of tetrapods A subset of tetrapods, amniotes produce eggs that allow embryos to develop away from water

Key Terms tetrapod Vertebrate with four legs, or a descendant thereof amniote Vertebrate in which the embryo develops surrounded by fluid enclosed by membranes inside the egg

Evolutionary Tree of Vertebrates

Fig 24.3, p. 379 Vertebrates Craniates Chordates Tetrapods Amniotes ancestral chordate Bony appendages Amniote eggs Swim bladder or lung(s) Backbone Tunicates Reptiles (with birds) Lancelets Jaws Four limbs Cartilaginous fishes HagfishesLampreys Ray-finned fishes Lobe- finned fishes Mammals Amphibians Braincase Evolutionary Tree of Vertebrates

Key Concepts Characteristics of Chordates Four traits characterize chordate embryos: a supporting rod (notochord), a dorsal nerve cord, a pharynx with gill slits in the wall, and a tail that extends past the anus Certain invertebrates and all vertebrates belong to this group

ANIMATION: Vertebrate Evolution To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

24.3 The Fishes The number and diversity of fishes exceed those of all other vertebrate groups combined Fishes are divided into jawless and fishes with jaws Fishes with jaws are divided into cartilaginous fishes and bony fishes

Jawless Fishes The first fishes were jawless – two lineages survive – both have a cylindrical body, no fins or scales, and move with a wiggling motion hagfish Jawless fish with a cranium (skull case) but no backbone lamprey Jawless vertebrates with a backbone of cartilage Some are parasites of other fish

Two Modern Jawless Fishes Hagfish Parasitic lamprey

Fishes With Jaws Jawed fishes likely evolved from jawless ancestors when some gill supports became modified Jawed fishes typically have scales and paired fins Jawed fished are divided into the cartilaginous fishes and the bony fishes

Proposed Evolution of Jaws

Fig 24.5, p. 380 supporting structure for gill slits jaw, derived from support structure jaw location of spiracle (modified gill slit) jaw support gill slits Proposed Evolution of Jaws

jaw location of spiracle (modified gill slit) jaw support jaw, derived from support structure Fig 24.5, p. 380 supporting structure for gill slits gill slits Stepped Art Proposed Evolution of Jaws

Cartilaginous Fishes (Chondrichthyes) Cartilaginous fishes include sharks and rays Some sharks have rows of teeth, some are filter feeders Rays include filter feeders (mantas) and bottom feeders (stingrays) cartilaginous fish Fish with a skeleton of cartilage Gills are visible at the surface

Two Cartilaginous Fishes

Bony Fishes There are two lineages of bony fishes: Ray-finned fishes are the most diverse, including salmon, sardines, bass, swordfish, trout, tuna, halibut, carp, and cod Lobe-finned fishes include coelacanths and lungfishes

Key Terms bony fish Fish with a lung or swim bladder and a skeleton consisting largely of bone lobe-finned fish Fish with fleshy fins that contain bones ray-finned fish Fish with fins supported by thin rays derived from skin; member of most diverse lineage of fishes

Bony-Fish Body Plan Aspects of the fish body plan adapt fish to life in water: A swim bladder allows ray-finned fish to adjust its buoyancy Kidneys filter blood and adjust volume and solute composition Lungfishes have gills and one or two air-filled lungs

Body Plan of a Perch

Fig 24.7a, p. 381 liverintestine ovarynerve cord stomachanusgills brain heart swim bladder kidney Body Plan of a Perch

Ray-Finned Fish Diversity

ANIMATION: Bony fish body plan To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

Lungfish: A Lobe-Finned Fish Pelvic and pectoral fins are supported by bones

Fig 24.8, p. 381 pectoral finpelvic fin Lungfish: A Lobe-Finned Fish

Key Concepts The Fishes The first vertebrates were jawless fish Most modern fishes have jaws Sharks and their relatives are jawed fishes with a cartilage skeleton Ray-finned fishes and lobe-finned fishes are jawed bony fishes Ray-finned fishes are the most diverse vertebrate group

ANIMATION: Jawless Fishes To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

ANIMATION: Evolution of Jaws To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

ANIMATION: Cartilaginous Fishes To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE