Unit 3: Grow a Backbone! Outcome: Identify and describe the characteristics of chordates. Vertebrates represent less than 5% of the animal species on earth, yet we are most familiar with vertebrates because “they are us” as Pogo said. The vertebrates possess a backbone consisting of a string of cylinders of bone called vertebrae surrounding a spinal protecting cord. They have an internal skeleton (endoskeleton) which starts as cartilage in the embryo and is replaced by bone in most groups as the animal matures. Bone consists of a mixture of living cells and calcium phosphate salts and is unique to the vertebrates. Calcium in invertebrates’ skeletal structures is usually calcium carbonate. The vertebrates share their phylum – Chordata – with one odd group of invertebrates, tunicates. Tunicates are soft, squishy blobs most commonly seen growing on pier pilings and floating docks. They do not appear to be related to vertebrates, but a careful study of the embryological development of both groups reveals the common characteristics that result in their placement in the same phylum. Fish comprise the most numerous members of the vertebrates, both in terms of species numbers (48%) and numbers of individuals.   Drill Questions: What is a vertebrate? What are some characteristics that connect us all together? What Phylum are vertebrates in? What are tunicates?

Classifications Kingdom Phylum Class Order Family Genus Species For now you will only need to know these three for the fishes Know that when Genus and Species are written that the “genus” is capitalized and the “species” is lower case EXAMPLE: Homo sapiens

Chordates Kingdom Animalia Phylum Chordata Organisms that possess at one point in life or another: Notochord Hollow dorsal nerve cord Pharyngeal gill slits Post anal tail

Chordates Kingdom Animalia Phylum Chordata Hollow Dorsal Nerve Cord: - Nerve cord that is modified into the brain and spinal nerve cord - Runs dorsal (above) the notochord

Chordates Kingdom Animalia Phylum Chordata Notochord: -Flexible rod is replaced by the vertebrae (backbone) - Runs below (ventral) the hollow dorsal nerve cord

Chordates Kingdom Animalia Phylum Chordata Pharyngeal Gill Slits: -Slits after the mouth that allow water to pass over but not go into the stomach - In mammals these disappear prior to birth, but in fishes they persist through adulthood.

Chordates Kingdom Animalia Phylum Chordata Post Anal Tail: -Muscular region of the body that extends passed the anus - Present in Homo sapiens when in the embryonic stage and in fish during adulthood

Above is Amphioxus, Lancelet, a primative marine chordate. Today you will be viewing amphioxus under the microscope and drawing the image making sure to label the: Hollow Dorsal Nerve Cord Notocord Pharyngeal Gill Slits Post Anal Tail When completed turn in the notes and lab.

Fish Classification Kingdom Animalia Phylum Chordata Class: Agnatha: Jawless Fish EX: Hagfish/Lampreys Chondrichthyes: Cartilaginous, Jaw Fish EX: Sharks/Rays/Skates/Sawfish Osteichthyes: Bony, Jaw Fish EX: Coelacanth/ Salmon/Parrot fish/Puffer fish

Class Agnatha Hagfish Lamprey Jaws Jawless Fins No Paired Fins Juvenile life Marine water – scavenger Fresh water – Filter feeder Adult life Marine water – Parasite Defense Mechanism Slime glands ---------------------------

Class Chondrichthyes Sharks Cartilaginous skeletons Fins: Dorsal, Caudal, Pectoral, Pelvic, and Anal Senses: Lateral Line, Ampullae of Lorenzini, and one drop of blood in one million parts water No swim bladders – Nitrogenous livers

Class Chondrichthyes Rays VS Skates Both have cartilaginous skeletons Both have enlarged pectoral/reduced dorsal & pelvic fins Breathing adaptation: Spiracles No swim bladders – Continuously Swim Rays: Fins flap like wings on a bird Skates: Fins move like waves Defenses: Rays: 220V shock and poison barbs on spine tail

Class Osteichthyes Bony Fish Bone skeleton Fins: Dorsal, Caudal, Pectoral, Pelvic, and Anal Senses: Lateral Line Swim bladders Defenses vary widely: inflation to spined tails

Pigments The use of specialized cells in the skin that contain pigment granules, called chromatophores, to blend with their environment, like the flounder or the squid/octopus/cuttlefish.

Countershading Blending in with the open ocean by having a dark green or blue-gray colored dorsal side and a white colored ventral side

Cryptic Colors Coloration or body features that mimic the environment around them, like sea horses.

Poster Colors Bright showy color patterns Show territorial ownership, sexual displays, or to show they are poisonous as

Reproduction Internal External Without direct maternal nourishment Shark egg case (nourishment inside case) With direct maternal nourishment Pregnant Shark (direct nourishment) External Lays eggs External to the parent

Hermaphrodites Sequential Hermaphrodites Synchronous Hermaphrodites Protogyny: Females change to Males EX: Parrot Fish Protandry: Males change to Females EX: Clown Fish Synchronous Hermaphrodites Functional male and female sex organs Hamlets