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Phylum Chordata & Types of Fish Kingdom Animalia Phylum Chordata Subphylum Urochordata Subphylum Cephalochordata Subphylum Vertebrata Class Agnatha Class Chondrichthyes Class Osteichthyes Phylum Chordata ● ● ● ● “Chordates” Contains invertebrate and vertebrate species All have bilateral symmetry All at one point have a notochord, dorsal nerve cord, pharynx, and gill slits Notochord ● ● A long rod of stiffened tissue Not bone or cartilage Nerve Cord ● ● Tube found on the dorsal side that runs parallel to the notochord and gut Anterior end enlarges during development to form brain Pharynx ● A muscular tube that acts in feeding, respiration, or both Gill Slits ● A means of removing oxygen from a liquid environment for respiration Subphylum Urochodata ● ● ● ● Includes: Tunicates or Sea Squirts Similar niche to sponges but far more complex animal Filter feeder, diatoms and other bits of food caught in gill slits Leathery “tunic” secreted and covers the body Subphylum Cephalochordata ● ● ● ● ● Includes: Lancelets (called due to shape) Shows the four distinct characteristics of chordates Closed circulatory system Respiratory gases diffuse across the body Filter feeders Subphylum Vertebrata ● 7 Current Classes: ◦ ◦ ◦ ◦ ◦ ◦ ◦ Agnatha – jawless fish Chondrichthyes – Cartilaginous fish Osteichthyes – Bony fish Amphibia – Amphibians Reptilia – Reptiles Aves – Birds Mammalia - Mammals Characteristics of Vertebrates: ● ● Many chordata characteristics seen in embryo stage Nerve cord develops into a spinal cord and a brain Two Large Advances: ● ● Spinal cord is protected by a bony vertebrae Brain is protected by a bony skull Complex Characteristics ● ● Expansion of species began with the evolution of a jaw developed from the structure supporting the gill slits This lead to the ability to hunt other animals and thus led to advances in the nervous system and other body system processes More Complex Characteristics ● Development of fleshy and skeleton fins that became the starting point for arms, legs, and wings ● Evolution of gills allowed for better diffusion of oxygen ● Gills developed into pouches then developed into lungs Quiz quetions ● ● ● ● ● ● What do all organisms is the phylum Chordata have at some point in their development? What does the nerve cord develop into? What do all vertebrates have? What is the long rod of stiffened tissue called? What is the function of gill slits? What type of symmetry do chordates have? Ichthyology ● The study of fishes Class Agnatha ● “Jawless Fishes” ● Most primitive fish ● Lacks jaws and feed by suction ● Cylindrical and elongated body ● Lack paired fins and scales Hagfish & Lampreys ● Hagfish ◦ Feed mostly on dead or dying fish ● Lampreys ◦ Mostly freshwater ◦ Attach to other fish and suck their blood Hagfish and lamprey dissection Quiz Questions What does the word “agnatha” mean? ● State the 3 things the class Agnatha lack. ● Which Agnatha feeds mostly on dead or dying fish? ● What is the study of fish called? ● Class Chondrichthyes ● “Cartilaginous Fish” ● Skeleton made of cartilage ● Movable jaws with well-developed teeth ● Rough sand paper like scales made of the same composition of the teeth Ampullae of Lorenzini ● Can detect very weak electrical fields ● Used to locate prey and navigate Lateral line ● The lateral line is present in most fish and is used to sense tiny vibrations in the water. It is situated just under the skin (subcutaneous) on the snout and along either side of the shark’s body. The lateral lines are canals that are filled with fluid. Tiny modified hair cells line its walls and are instrumental in sensing vibrations and movement. Lateral line continued ● ● ● ● Interestingly, the lateral line can also locate odor plumes. These are 3dimensional structures that assist the shark (and other bony fish) to detect prey as well as potential mates. Interestingly, when the lateral line of sharks is covered up or chemically impaired (as is the case when treated with certain antibiotics), they are often unable to detect these odor plumes or their sensory perception is somewhat limited, despite the fact that their nostrils are fully exposed and functional. Usually, fish and sharks will use the combination of smell and turbulence detection at the same time. This process is called "eddy chemotaxis". When a person, seal or other animal moves through the water, they leave behind them a wake (turbulence), which is infused with their body smell (odor). This is referred to as an "eddy". While it is optimal for the shark to be able to see its prey, it is really the combination of the lateral line and its sense of smell that makes for prime hunting abilities and opportunities for the animal. This is thought to be the reason that sharks often bump and rub up against objects and even divers, as it is believed to assist them to ‘taste’ whether it is suitable for consumption as they move the object against their lateral line. Sharks & Ratfish ● Sharks ◦ Adapted for fast swimming and to be predators ● Ratfish or Chimeras ◦ Bottom dwellers ◦ Have long “rat-like” tails Rays and Skates ● Rays ◦ Flattened bodies with gills on the bottom of their bodies ◦ Whip-like tail with stinging spines (venomous) ● Skates ◦ Very similar to rays but without the long tail or stinging spines ● ● ● ● ● https://www.youtube.com/watch? v=xEpmQtQGay4 (facts about stingrays) https://www.youtube.com/watch? v=He24uTIoz-0 (giant rays) https://www.youtube.com/watch? v=iLwkfWuAMRo (Jonathan Birds Skates and Rays) https://www.youtube.com/watch? v=vrkkQO9zVfA (bull shark Jonathan Bird) https://www.youtube.com/watch? v=vkkBEioUS8U (shark dissection) Rays Jonathon Bird Skates and Bullshark Shark dissection Quiz Questions ● ● ● ● ● ● What does “chondrichthyes” mean? Describe the scales on chondrichthyes. List the 4 organisms in this class. Describe the difference between rays and skates. What is the function of the lateral line? Electrical impulses are detected by what? Class Osteichthyes ● ● ● ● ● ● “Bony Fish” Make of 98% of all fish and over half the vertebrates Skeleton at least made partially of bone Thin, flexible, overlapping scales Mouth located at end of body Presence of gas-filled sac called a swim bladder Body Shape ● Body shape is varied and linked to its lifestyle ● Fast swimmer need elongated bodies Body Shape ● Short, compressed bodies good for navigating tight places like reefs ● Bottom dwellers tend to have flattened shapes Body Shape ● Elongated shapes are need for life in narrow spaces ● Some have less generalized shapes Body Shape ● Some shapes are conducive to camouflage with their environment Exterior Layer Locomotion ● Fish swim with rhythmic side to side motion of the body or tail ● Rhythmic contractions produced by bands of muscle called myomeres Locomotion ● Swim bladder – specialized organ filled with gas that assists in floating due to a heavier bone structure (found in bony fish) Pectoral Fins ● Oversized in sharks to provide lift due to no swim bladder, provide tight maneuverability in bony fish Dorsal & Anal Fins ● Employed as rudders used to steer and provide stability Pelvic fin ● Help the fish turn, balance, and brake Caudal (tail) fin ● Used in steering and force production Lobe-Finned Fish ● ● ● Link between water based fish and land dwelling amphibians Developed bone/cartilage appendages that allowed them to move in mud and shallow waters Developed primitive lungs as well Digestion ● Food passed through esophagus into the stomach for digestion and on into an intestine Digestion ● Pancreas, liver, and the pyloric caeca secrete digestive enzymes Respiratory System ● Fish get oxygen that is dissolved in the water ● They must get water to flow over gills to do this, called irrigation Gill Structure The gill is supported by cartilaginous or bony structure called gill arch ● Gill rakers are used as filters to stop food from entering gills ● Gill filaments contain the capillaries ● Circulatory System ● Closed circulatory system ● Two chambered heart ● Gas exchange happens in the gills Lungfish ● Uses actual lungs to breathe and has reduced gills Regulating Internal Environment The blood of marine fish is less salty than the water, therefore they lose water through osmosis ● To replace it they must drink seawater ● Nervous System Central nervous system consisting of brain ● Highly developed sense of smell due to olfactory bulb/sacs which open to the ● Nervous System ● Some bottom feeders like catfish have whisker like organs called barbels Lateral Line ● Unique sense organ that enables them to detect vibrations in the water ● Canals inside the body connected to surface by pores Seahorses and lungfish National Geographic deep water fish (long) Fish Documentary Quiz Questions ● ● ● ● ● ● ● ● What does “osteichthyes” mean? What body shape do fast swimmers need? What is the function of the swim bladder? Why do sharks not need this organ? What are lobe-finned fish? What are gill rakers? Describe the circulatory system. What are the whisker like organs on some bottom feeders called? Endothermic or exothermic?