Click on a lesson name to select. Chapter 28 Fishes and Amphibians Section 1: Fishes Section 2: Diversity of Today’s Fishes Section 3: Amphibians

Characteristics of Vertebrates  Vertebrates have a vertebral column and specialized cells that develop from the nerve cord. Fishes and Amphibians Chapter 28  Classes of vertebrates include fishes, amphibians, reptiles, birds, and mammals Fishes

Vertebrates More than 99% of Chordates are Vertebrates Skeletons are composed of hard bone that left behind a great fossil record A vertebrate animal is…. –In the phylum Chordata –Subphylum Vertebrata – posses a notochord only during early stages of development Notochord is replaced by a vertebral column (spine)

Background of Vertebrates – Permian Extinction Permian Period ended about 245 mya with one of the most devastating mass extinctions in the entire history of the earth Killed nearly all marine animals (95%) Gave way to the Mesozoic era with the ruling of the reptiles

Mesozoic Era Reptiles of the sea (turtles, crocodiles, lizards, snakes) and reptiles of the land (dinosaurs) ruled the earth Birds then evolved from a small group of flesh eating dinosaurs Mammals appeared 300 mya Cretaceous Extinction 65 mya signaled the end of the dinosaurs –asteroid? Global cooling? Volcanic eruptions?

Living Vertebrate Groups Jawless fishes (lamphreys) Cartilaginous Fishes (Sharks/Rays) Bony Fishes (sea horse) Amphibians (frogs/salamanders) Reptiles (snakes/crocs/turtles) Birds (finches/hawks/flamingos) Mammals ( all mammals that have hair/fur, nourish young with milk)

Earliest Vertebrates-Trend #1 - Jaws Jawless Fishes Their mouths were not efficient Trend 1 = development of jaws! –Usable and adaptable feeding tool

Trend #2-Girdles Development of paired pectoral and pelvic girdles Connects backbone to front limbs and connects backbone to hind limbs Therefore for fishes, it allows them to evolve complex and useful fins

Trend #3 - Bones The Development of Bones!! Bones of fish eventually developed the ability to support structures such as arms, legs that support weight, bones in wings etc. Having 4 limbs = tetrapods VIDEO – Lobe-Finned Fish

Vertebral Column  A vertebral column made of cartilage or bone surrounds and protects the dorsal nerve cord. Fishes and Amphibians  The vertebral column functions as a strong, flexible rod that muscles can pull against during swimming or running Fishes Chapter 28

Neural Crest  A neural crest is a group of cells that develop from the nerve cord in vertebrates. Fishes and Amphibians  Portions of the brain and skull, certain sense organs, and some nerve fibers are some of the structures that develop from the neural crest Fishes Chapter 28

Characteristics of Fishes  Fishes are found in a variety of habitats including seas, lakes, ponds, streams, and marshes. Fishes and Amphibians  Most fishes have vertebral columns, jaws, paired fins, scales, gills, and single-loop blood circulation Fishes Chapter 28

Self- inflating fish Bizarre fish

Jaws  Anterior gill arches evolved into jaws in ancient fishes. Fishes and Amphibians  The development of jaws allowed ancient fishes to prey on a larger range of animals Fishes Chapter 28

Paired Fins  A fin is a paddle-shaped structure on a fish or Fishes and Amphibians 28.1 Fishes Chapter 28 other aquatic animal that is used for balance, steering, and propulsion.  Paired fins reduce the chance of rolling to the side and allow for better steering during swimming.

Scales  There are four types of fish scales. Fishes and Amphibians  Ctenoid scales  Cycloid scales  Placoid scales  Ganoid scales 28.1 Fishes Chapter 28

Placoid Scales Ctenoid Scales

Gills  Fishes get oxygen when water that enters their mouths flows across their gills, where oxygen from the water diffuses into the blood. Fishes and Amphibians  Gills are composed of thin filaments that are covered with highly-folded, plate-like lamellae Fishes Chapter 28

Circulation  Vertebrates have a closed circulatory system. Fishes and Amphibians  In most fishes, the heart consists of two main chambers—the atrium and the ventricle Fishes Chapter 28

Feeding and Digestion  Most fishes swallow their food whole, passing it through a tube called the esophagus to the stomach, where digestion begins. Fishes and Amphibians 28.1 Fishes Chapter 28

Excretion  Cellular wastes are filtered from fishes’ blood by the kidneys. Fishes and Amphibians  A nephron is a filtering unit within the kidney that helps maintain the salt and water balance of the body and to remove cellular waste products from the blood Fishes Chapter 28

The Brain and Senses  Color vision, chemical detection, hearing, and balance are coordinating in the brain. Fishes and Amphibians  The lateral line system is a special sensor that allows fish to detect even the slightest movements in water Fishes Chapter 28

Reproduction  The majority of fishes reproduce through external fertilization. Fishes and Amphibians  Male and female fishes release their gametes near each other in the water in a process called spawning Fishes Chapter 28

Movement  Fishes are well adapted to swimming in the water Fishes Fishes and Amphibians  Streamlined shape  Paired fins  Swim bladder  Fishes move through the water by contracting muscle groups on either side of their bodies. Chapter 28

Classes of Fishes  Scientists have grouped fishes into three classes based on their body structure. Fishes and Amphibians  Jawless fishes  Cartilaginous fishes  Bony fishes 28.2 Diversity of Today’s Fishes Chapter 28

Jawless Fishes  Hagfish feed on soft-bodied invertebrates and dead or dying fish on the sea floor. Fishes and Amphibians Lamprey  Lampreys are parasites that feed by attaching themselves to other fishes Diversity of Today’s Fishes Chapter 28

Cartilaginous Fishes  All cartilaginous fishes have skeletons made of cartilage. Fishes and Amphibians  The flexible skeleton, rows of sharp teeth, a streamlined body, and placoid scales make sharks one of the top predators in the sea.  Skates and rays have flattened bodies that are adapted for living on the ocean floor Diversity of Today’s Fishes Chapter 28

Bony Fishes  There are two groups of bony fishes: the ray- finned fishes and the lobe-finned fishes. Fishes and Amphibians  Thin, spinelike rays support the fins of ray-finned fishes.  Lobe-finned fishes have muscular lobes and joints similar to those of land vertebrates Diversity of Today’s Fishes Chapter 28

28.2 Diversity of Today’s Fishes Fishes and Amphibians Evolution of Fishes Chapter 28

Fishes and Amphibians 28.3 Amphibians Chapter 28

National Geographic – Water Frog

Characteristics of Amphibians  Most amphibians begin life as aquatic organisms. Fishes and Amphibians  After metamorphosis, they are equipped to live life on land Amphibians Chapter 28 Tadpole Frog

Feeding and Digestion  Most frog larvae are herbivores, whereas salamander larvae are carnivores. Fishes and Amphibians  As adults, their diets are similar as both groups become predators.  The digestive system of an amphibian is very similar to that of a fish Amphibians Chapter 28

Excretion  Amphibians filter wastes from the blood through their kidneys, and excrete either ammonia or urea as the waste product. Fishes and Amphibians  Ammonia is excreted by amphibians that live in the water.  Urea is stored in the urinary bladder until it is eliminated from the body through the cloaca Amphibians Chapter 28

Respiration  As larvae, most amphibians exchange gases through their skin and gills. Fishes and Amphibians  As adults, most breathe through lungs, their thin, moist skin, and cavities in the mouth Amphibians Chapter 28

Circulation  Amphibians have a double-loop circulatory system. Fishes and Amphibians  Amphibians have three-chambered hearts Amphibians Chapter 28

The Brain and Senses  Amphibians use sight to locate and capture prey that fly at high speeds and to escape predators. Fishes and Amphibians  Frogs have nictitating membranes that protect their eyes.  Frogs use their tympanic membrane to hear high- pitched sounds and to amplify sounds from the vocal cords Amphibians Chapter 28

Reproduction and Development  In most amphibians, fertilization is external and the shell-less eggs must be laid and fertilized in water. Fishes and Amphibians  Tadpoles hatch from the egg and undergo metamorphosis from a fishlike animal to an air-breathing one Amphibians Chapter 28 Virtual Frog Dissection

Amphibian Diversity  Scientists classify modern amphibians into three orders. Fishes and Amphibians  Order Anura includes frogs and toads.  Order Caudata includes salamanders and newts.  Order Gymnophiona includes caecilians Amphibians Chapter 28

Evolution of Amphibians 28.3 Amphibians Fishes and Amphibians Chapter 28