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• PHYLUM CHORDATA KEY CONCEPT All vertebrates share common structures and characteristics. • Most chordates lose some or all of these characteristics in adulthood. Key concept all vertebrates are chordates not all chordates are vertebrates Sea squirts Subphylum. Urochordata Subphylum. Vertebrata Subphylum. Cephalochordata Phylum.Chordata Chordata Lancelet Phylum Chordata contains all vertebrates • Chordates share common features or structures at some stage of development at some point in their life cycle. – Notochord • Long, firm rod that extends along the back of the animal becomes the vertebral column – Hollow nerve cord • Hollow tube that in chordates that becomes the brain and spinal cord hollow nerve cord – pharyngeal slits tail notochord • Gills in the throat region – Postanal tail pharyngeal slits brain Dorsal nerve cord Postanal tail Pharyngeal slits • • • • • • • Chordate Characteristics Bilateral symmetry Two pairs of appendages Cephalization Closed circulatory system Coelom – body cavity that contains vital organs Internal skeleton deuterostomes •An endoskeleton allows vertebrates to grow to large sizes. •internal •made of bone or cartilage • An endoskeleton can be divided into two parts. – Axial skeleton – braincase (cranium) – vertebrae braincase Pectoral girdle vertebrae – Appendicular skeleton Pelvic girdle – Pectoral girdle – Pelvic girdle More complex for better motor control Sensory detection of the animals environment (brain) Skeleton becomes stronger to work with bigger muscles Allows more rapid movement nervous skeletal Stronger heart to circulate blood faster circulation Adaptations respiration Digest more food Muscularized gut parastalsis Digestive glands Liver Pancreas digestive Gill slit and muscular pharynx will move more water over gills More oxygen is extracted from water DON’T COPY Subphylum Urochordata • Sea squirt • Gill slits (pharyngeal slits) • Notochord – Only in larva • Adult has tunic DON’T COPY Subphylum Cephalochordata Lancelet • Amphioxus • Notochord length of body • Dorsal hollow nerve cord • Gill slits • Segmented muscles Amphioxus • There are seven classes of vertebrates. 1. Agnatha 2. Chondrichthyes 3. Osteichthyes 4. Amphibians 5. Reptilia 6. Aves 7. Mammalia Kingdom Animalia Phyla Chordates 7 classes characteristics Separation chacteristic Skeleton Circulation heart habitat appendages respiration Agnatha Chondrarithes osticthesis Amphibia Reptilia Aves mammalia Main Characteristic Osteichthyes Amphibia Aves Mammalia mammals bony fish cartilaginous fish Chondrichthyes jawless Agnatha 3. amphibia Four limbs 5 aves Feathers 2 JAWS Jaws 6 mammals Hair 1 Agnatha Jaw is missing. 4 reptiles scales • There are 30,000 species of Fish – 20,000 are Marine. • The dominant aquatic vertebrates are the fish. • 97% of fish are bony fishes. • They belong to Phylum Chordata. • Most fish use counter shading as a means of camouflage. Characteristics of All Fish 1. They are aquatic 2. They are cold blooded 3. They have a backbone 4. They have paired fins 5. They breath with gills 6. Lateral line system 7. Developed brain Fish are vertebrates with gills and paired fins. • Fish use specialized organs called gills to breathe underwater. – sheets of thick, frilly tissue filled with capillaries – take in dissolved oxygen from water, release carbon dioxide – Have countercurrent flow water flow • Fins are appendages that project from a fish’s body. – keep fish stable – redirect water around fish as it swims – help fish maneuver in water • All fish have a lateral line system. – sensory system – sensitive to small changes in water movement lateral line Parts of the fish brain Olfactory lobe cerebrum Optic lobe cerebellum Medulla body regions of a fish thorax tail . head Fins Pelvic Fin Class Agnatha • Tunicates (worms) may be the closest relatives to vertebrates. • The first recognizable vertebrates were jawless fish. • Two groups of jawless fish still exist today. – lampreys hagfish Lampreys • Characteristics – Jawless – http://dsc.discovery.com/videos/dirty-jobs-sealamprey-exterminator/ – Smooth skin teeth – Cylinder-like bodies – Bones made of cartilage – parasitic mouth •Mouth structures •Sucker like mouth •Rasping teeth •Oral disk Oral disk Feeding •Fasten to the side of a fish •Flip their body •scrap a hole in the side Reproduction •Suck out the blood & tissues reproduction • • • • • Freshwater lakes and streams Lay eggs in hollows made in gravel Eggs are fertilized externally Worm like larvae hatch and burrow into the gravel They remain there for 3 years Hagfish • • • • • • • • • Bottom dwellers Cold ocean waters 5 – 15 pairs of gills Mucus-secreting glands all over their bodies Sometimes called slime eels Poorly developed eyesight Slit-like toothed mouths Scavengers Hermaphrodites – Produce sperm one year and eggs the next – Internal fertilization – Young hatch and look like the adult Only two groups of jawed fish still exist. • Cartilaginous fish and bony fish are still in existence. Jaws evolved from gill supports. • Jaws developed from gill arches located around the pharynx. cranium cranium cranium mouth gill arches mouth mouth • Jaws gave vertebrates a huge advantage as predators. Class Chondrichthyes Cartilaginous fish have skeletons made of cartilage Orders – Holocephali include ratfish, a small group of deep-sea fish. – Elasmobranchs include sharks, rays, and skates. Rat fish There are 300 species of cartilaginous fish characteristics • Jaws lined with rows of teeth that are constantly replaced • Skin is covered with small pointed teeth – placoid scales • 5 – 7 pairs of gills • Two chambered heart • Separate sexes • Fertilization is internal • Marine • Carnivorous • Detect prey with lateral lines system Sharks • Liver controls their buoyancy • Dermal denticles - teeth like scales allow them to taste with their skin • Ampullae of Lorenzini in their jaws allow them to sense electrical impulses • They are all muscles and skin and can’t take much abuse Skates/Rays • Have gills on their ventral side • use spiracles to breath on top of their head • primarily feed on mollusks, crustaceans, worms, and occasionally smaller fishes. Some rays crush their prey between their blunt teeth, sometimes referred to as bony plates • Often completely burying themselves in the sand or soft sediment • camouflaged by a grayish-brown, often mottled coloration Skates/Rays • More than 200 species have been described, in 27 genera • slow growth rates and, since they mature late, low reproductive rates • Among the best know rays are stingrays, which have long, slim, whiplike tails armed with serrated, venomous spines. A stingray lashes its tail only as a defensive measure when it is caught, stepped on, or otherwise disturbed. Southern Stingray Butterfly Ray Gymnura micrura Absence of a Barb – sharp spines Dasyatis americana Absence of a Barb Absence of a Barb – sharp spines Clearnose Skate Presence of a Barb Omit Great whites and the red triangle 1. Where is the greatest concentration of great whites in the US 2. Why is it called the red triangle? 3. What are the main food sources of the sharks? 4. Where is the red triangle? 5. How often do sharks need to feed? 6. Where do they patrol? 7. What has caused the greatest reduction in their numbers? 8. What has been their saving grace? Ray on the left Skates on the right • The major difference between rays and skates is in their reproductive strategies. Rays are live bearing (viviparous) while skates are egg laying (oviparous), releasing their eggs in hard rectangular cases sometimes called "mermaid´s purses". Also, skates typically have a prominent dorsal fin while the dorsal fin is absent or greatly reduced in rays. • Most rays are kite-shaped with whip-like tails possessing one or two stinging spines while skates have fleshier tails and lack spines. Rays protect themselves with these stinging spines or barbs while skates rely on thorny projections on their backs and tails to for protection from predators. • rays are generally much larger than skates. External structures female Muscles tissue male liver Internal structures Gill slits External Shark Anatomy Lab 1. Draw the lateral view of 1. Fins the shark • Anterior dorsal 2. Label the following • Posterior dorsal structures • Caudal • Lateral line • Spiracle • Eyes • Gill slits • rostum • Pelvic • pectorial Ventral 1. Label the fins 2. Label the following structures • Clasper • Cloacal opening • Gill slits • Nostrils • Mouth • ampullae of Lorenzini 1. Chart all of the view structures and functions 2. Chart the fins give the name, number and function 3. Sex your shark 4. What is the number of teeth rows 5. What is the number of gill slits 6. Describe the feel of the shark Internal examination of the shark • • • • Draw and label each system Chart each system List all structures in bold print Give their function