Chapter 12 Handout- Chondrichthyans - BIOL 3705 Chapter 12 The Chondrichthyans Name Zoelle Reinke Instructions Complete the following handout as

Chapter 12 Handout- Chondrichthyans - BIOL 3705 Chapter 12...

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BIOL 3705 Chapter 12: The Chondrichthyans Name: Zoelle Reinke Instructions- Complete the following handout as thoroughly as possible using your textbook and Moodle Powerpoint files to assist you. Type your answers into this document, print, and turn in by the due date. Handouts are to be completed by each student independently. This handout is worth 40 points. Section 1: Group description. Provide a brief description of each taxonomic groups using appropriate characteristicsElasmobranchii- (subclass) and means sharklike fishes. They have cartilaginous skeleton, placoid scales, internal fertilization, replacement dentition, and have multiple gill slits. Euselachii- (order) – This includes requiem/ ground sharks, lamniform sharks, squaliform sharks, and rajiform. They all have large size, marine habitats, mobility, slow metabolism and slow growth, predatory feeding habits, reliance on nonvisual senses, low fecundity, precocial young, and vulnerability to exploitation.Holocephalimorpha- (subclass) that means “complete heads”. They usually live close to the bottom and eat mollusks and invertebrates. They have a long, thin tail. Sometimes they can have a spine in front of their dorsal fin that is poisonous. They are chimaera or ratfish. They also are found in deep water and have elaborate rostral extensions. Lamniformes- (order) Theses have pelagic habitats. Some include Mako, white, thresher, and basking sharks. They have two dorsal finesse, one anal fine, and five gill slits. They also have a higher body temperature than the water around them. They have very large teeth and are very fast swimmers.Squaliformes- (order) these include dogfishes in colder habitats. They have two dorsal fins, no spines, no anal fin, and five gill slits. They have rougher skin. Their dorsal spines contain venom and is mildly toxic to humans. Their liver and stomach has sqaulamine in them which causes with the reduction of small blood vessel growth in humans.Rajiformes- (order) these are flattened with large pectoral fins which include skates and stingrays. Their eyes and spiracles are the upper surface of their head and their gill slits are on the underside of their body. They are dorsoventrally flattened. Section 2: Fill in the blankChondrichthyians consist of approximately ____________ 800 living species. Chondrichthyans known as sharks are the most popular groups with about _436_ extant species.Chondrichthyans lack lungs or gas bladders, but have large __livers which provide buoyancy.Although _internal_ fertilization is rare in most bony fishes, it is universal in all Chondrichthyans.Most elasmobranchs occur in _marine habitats_.Chondrichthyans may have symmetric tails, but most exhibit __asymmetric heterocercal__ tails.Elasmobranch home ranges generally _increases__ with age.

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