Nonvertebrate Chordates, Fishes, and Amphibians Ms. Moore 3-1-13

What is a Chordate? Phylum: Chordata A chordate is an animals that has, for at least some stage of life, a dorsal, hollow nerve cord; a notochord; pharyngeal pouches; and a tail that extends beyond the anus. Hollow nerve cord: nerves branch off and connect to organs Notochord: long supporting rod that runs through the body just below the nerve cord Pharyngeal pouches: paired structures in the throat region; can develop slits  gills in some chordates Tail: can contain bone and muscle; can be used for motility

Characteristics of Chordata

Most Chordates are Vertebrates Figure 30-2 96% of all chordates are placed in the subphylum: Vertebrata  vertebrates Vertebrae: backbone replaces the notochord in most developing vertebrates; encloses and protects the spinal cord Part of endoskeleton Grows as the animal grows Made up of living and non living cells

Nonvertebrate Chordates 2 groups of Chordata do not have a backbone Soft bodied marine animals 550 mya = ancestors! Tunicates Subphylum: Urochordata Filter feeders Open Circulatory Lancelets Subphylum: Cephalochordata Small fishlike creatures Live on sandy ocean body Closed Circulatory Diffusion through skin

Mini Lab Draw a picture depicting a typical: Label all parts Tunicate (p 769) Lancelet (p 770) Label all parts

What is a Fish? Fishes are aquatic vertebrates, most fishes have paired fins, scales, and gills. Fins = movement Scales = protection Gills = exchanging gases

Evolution of Fishes The evolution of jaws and paired fins were important developments during the rise of fishes. First Fishes: 510 mya Jawless with armored plates The Age of Fishes: 505-410 mya Ancestors of hagfishes and lampreys Arrival of Jaws and Paired Fins Filter feeders  herbivores and carnivores Fins attached by cartilage  movement Cartilage: strong tissue that supports the body; softer and more flexible than bone Modern Fishes Ancestors of sharks and rays: cartilage Bony fishes: bone

Form and Function in Fishes Feeding Herbivores, carnivores, parasites, filter feeders, and detrius feeders Mouth  Esophagus  Stomach  other organs  Intestines  Anus

Respiration Circulation Gills: located on either side of the pharynx; made up of feathery filaments Lungs: specialized organs to help in shallow waters Circulation Closed circulatory system: single loop Heart  gills  body  heart Atrium: large muscular chamber located in the heart Ventricle: thick-walled, muscular chamber; pumping portion of the heart

Response Fishes have well-developed nervous systems organized around a brain Cerebrum: voluntary activities; senses Cerebellum: coordination Medulla oblongata: fx of organs Lateral line system: sense vibration/movement Movement S-shaped movement—muscles in the back Fins increase surface area = faster Swim bladder: gas filled organ that adjusts buoyancy

Reproduction Eggs can be fertilized externally or internally Oviparous: eggs hatch outside the mother’s body; salmon Ovoviviparous: eggs stay in the mother’s body after internal fertilization; guppy Viviparous: embryos stay in the mother’s body after internal fertilization; some sharks

Groups of Fishes Jawless Fishes Sharks and Relatives Bony Fish Class: Agnatha No true teeth or jaws Skeletons made of fibers and cartilage (keep notochords) Include: lampreys—filter feeders as larvae/parasites as adults Hagfishes—detrius feeders; slime; 6 hearts; open; knots! Sharks and Relatives Class: Chondrichthyes (a.k.a. cartilage) Include: sharks, rays, skates, and others Bony Fish Class: Osteichthyes Skeleton made of bone Almost all include ray-finned fishes

Ecology of Fishes Aquatic Life Movement/Migration Freshwater = low salt concentration Ocean = high salt concentration Movement/Migration Anadromous fishes: ocean dwellers migrate to freshwater to breed Lampreys Salmon Catadromous fishes: freshwater fishes migrate to ocean to breed European eels

Mini Lab Draw the diagram of the fish, label all parts (p774) Draw the diagram of a fish brain, label all parts (p777) Fill out long study guide Agnatha  Osteichthyes Complete handout

What is an Amphibian? An amphibian is a vertebrate that, with some exceptions, lives in water as a larva and on land as an adult, breathes with lungs as an adult, has moist skin that contains mucous glands, and lacks scales and claws. Evoultion of Amphibians: Bones became stronger = movement on land Lungs = breath air Sternum = protection of organs

Form and Function in Amphibians Feeding Tadpoles: filter feeders or herbivores (algae) with long intestines Adult: meat-eating with shorter intestines Sticky tongues to catch prey Mouth  esophagus  stomach  intestine  liver/pancreas/gallbladder  colon  cloaca (digestive wastes, urine, eggs/sperm leave body) Respiration Larval: gas exchange through skin/gills Adult: lungs some skin/mouth cavity (always exceptions—lung less salamanders)

Circulation Excretion Reproduction Double loop system: first carries O2 rich blood from heart to lungs and skin and back; second carries O2 rich blood from heart to rest of body and back 3 chambers: left atrium, right atrium, and ventricle Excretion Kidneys  ureters  bladder/cloaca Reproduction Frog eggs laid in water to undergo external fertilization Eggs hatch into tadpoles Tadpoles gradually grow limbs, lose tails/gills, and become carnivorous Young adults move onto land

Movement Response Larva: move like fishes Adult: use front and back legs to move in a variety of ways Response Brain much like a fish Well developed nervous and sensory systems Nictitating membrane: protects eye from underwater damage/keeps moist Tympanic membrane: eardrums on each side of the head

Groups of Amphibians Salamanders (and Newts) Frogs and Toads Order: Urodela Long bodies and tails; most have 4 legs Larva and adults are carnivorous Moist environment or underwater Frogs and Toads Order: Anura Jump! Frogs = long legs, near water; Toads = shorter legs; moist woods, even deserts Caecillians Order: Apoda Legless, carnivorous, live in water or burrow in moist soil, many have fishlike scales in skin

Ecology of Amphibians Must live near water Protection from predators Some exceptions: desert amphibians have special adaptations Protection from predators Skin colorings/markings Poison glands in skin Global decline Amphibians are very susceptible to the environment

Mini Lab Draw the following in your lab manual: Figure 30-23 (p784) Notice the location of the organs Figure 30-24 (p785) Use different colors to demonstrate the direction of blood throughout the amphibian Create a life cycle for an amphibian Can use figure on p786