Vertebrata (& Rotifera) Rotifera. Structures 11/06/12. Chondrichthyes Osteichthyes Amphibia Reptilia Aves Mammalia

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1 Vertebrata (& Rotifera) Chondrichthyes Osteichthyes Amphibia Reptilia Aves Mammalia Rotifera A small phylum with about 1,800 species Essen;ally aqua;c Microscopic Mul;cellular Specialized organ systems Unusual reproduc;on Lophotrochoza Structures Pharynx with jaws (trophi) Alimentary canal, mouth & anus Pseudocoelom Hydrosta;c skeleton Crown of cilia Wheel Bearer 1

2 Reproduc;on Parthenogenesis Producing females only Sexual reproduc;on Some eggs produce males Resistant dormant embryos 100 million years Figure 33.2 Porifera ANCESTRAL PROTIST Cnidaria Common ancestor of all animals Eumetazoa Bilateria Lophotrochozoa Ecdysozoa Deuterostomia Figure 34.2a Echinodermata ANCESTRAL DEUTEROSTOME Notochord Common ancestor of chordates Head Vertebral column Jaws, mineralized skeleton Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Osteichthyes 2

3 Figure 34.2b Actinopterygii Lungs or lung derivatives Lobed fins Actinistia Dipnoi Amphibia Limbs with digits Amniotic egg Reptilia Mammalia Milk Derived Chordate Characteristics Notochord Hollow dorsal nerve cord Pharyngeal slits Post anal tail Are they all always present? Concept 34.3: Vertebrates are craniates that have a backbone During the Cambrian period, a lineage of craniates evolved into vertebrates Vertebrates became more efficient at capturing food and avoiding being eaten 2011 Pearson Education, Inc. 3

4 Derived Characters of Vertebrates Vertebrates underwent a second gene duplication involving the Dlx family of transcription factors Vertebrates have the following derived characters Vertebrae enclosing a spinal cord An elaborate skull Fin rays, in the aquatic forms Concept 34.4: Gnathostomes are vertebrates that have jaws Gnathostomes include sharks and their relatives, ray-finned fishes, lobe-finned fishes, amphibians, reptiles (including birds), and mammals 2011 Pearson Education, Inc. Chondrichthyes skeleton composed primarily of cartilage largest and most diverse group of chondrichthyans includes the sharks, rays, and skates A second subclass is composed of a few dozen species of ratfishes Figure 34.15a Dorsal fins Pectoral fins Pelvic fins (a) Blacktip reef shark (Carcharhinus melanopterus) 4

5 Figure 34.15b (b) Southern stingray (Dasyatis americana) Figure 34.15c (c) Spotted ratfish (Hydrolagus colliei) Shark eggs are fertilized internally but embryos can develop in different ways Oviparous: Eggs hatch outside the mother s body Ovoviviparous: The embryo develops within the uterus and is nourished by the egg yolk Viviparous: The embryo develops within the uterus and is nourished through a yolk sac placenta from the mother s blood 2011 Pearson Education, Inc. 5

6 The Sewer The reproductive tract, excretory system, and digestive tract empty into a common cloaca Osteichthyes Ray-Finned Fishes and Lobe-Fins Osteichthyans includes the bony fish and tetrapods Most fishes breathe by drawing water over gills protected by an operculum Fishes control their buoyancy with an air sac known as a swim bladder Fishes have a lateral line system Most species are oviparous, but some have internal fertilization and birthing Figure Brain Spinal cord Swim bladder Dorsal fin Adipose fin Caudal fin Nostril Cut edge of operculum Gills Kidney Heart Liver Stomach Intestine Gonad Anus Pelvic fin Urinary bladder Anal fin Lateral line 6

7 Figure Yellowfin tuna (Thunnus albacares) Red lionfish (Pterois volitans) Common sea horse (Hippocampus ramulosus) Fine-spotted moray eel (Gymnothorax dovii) Lobe-fins (Sarcopterygii) muscular pelvic and pectoral fins Three lineages survive and include coelacanths, lungfishes, and tetrapods Coelacanths were thought to have become extinct 75 million years ago, but a living coelacanth was caught off the coast of South Africa in 1938 Figure

8 Concept 34.5: Tetrapods are gnathostomes that have limbs One of the most significant events in vertebrate history was when the fins of some lobe-fins evolved into the limbs and feet of tetrapods Tetrapods have some specific adaptations Four limbs, and feet with digits A neck, which allows separate movement of the head Fusion of the pelvic girdle to the backbone The absence of gills (except some aquatic species) Ears for detecting airborne sounds 2011 Pearson Education, Inc. Figure Lungfishes Eusthenopteron Panderichthys Tiktaalik Acanthostega Limbs with digits Tulerpeton Amphibians Amniotes Silurian PALEOZOIC Devonian Carboniferous Permian Time (millions of years ago) Key to limb bones Ulna Radius Humerus Amphibia are represented by about 6,150 species Order Urodela includes salamanders, which have tails Order Anura includes frogs and toads, which lack tails Order Apoda includes caecilians, which are legless and resemble worms 8

9 Figure (a) Order Urodela (salamanders) (b) Order Anura (frogs) (c) Order Apoda (caecilians) A few characteristics Amphibian means both ways of life, referring to the metamorphosis of an aquatic larva into a terrestrial adult Most amphibians have moist skin that complements the lungs in gas exchange Fertilization is external in most species, and the eggs require a moist environment In some species, males or females care for the eggs on their back, in their mouth, or in their stomach Amniotes Amniotes are tetrapods that have a terrestrially adapted egg tetrapods whose living members are the reptiles, including birds, and mammals Amniotes are named for the major derived character of the clade, the amniotic egg, which contains membranes that protect the embryo The extraembryonic membranes are the amnion, chorion, yolk sac, and allantois 9

10 Figure Extraembryonic membranes Amnion Allantois Chorion Yolk sac Embryo Amniotic cavity with amniotic fluid Yolk (nutrients) Shell Albumen Reptilia The reptile clade includes the tuataras, lizards, snakes, turtles, crocodilians, birds, and the extinct dinosaurs Reptiles have scales that create a waterproof barrier Most reptiles lay shelled eggs on land Most reptiles are ectothermic, absorbing external heat as the main source of body heat Dinosaurs once ruled the biosphere dinosaurs diversified into a vast range of shapes and sizes They included bipedal carnivores called theropods, the group from which birds are descended Dinosaurs, with the exception of birds, became extinct by the end of the Cretaceous Their extinction may have been partly caused by an asteroid 10

11 Figure (a) Tuatara (Sphenodon punctatus) (b) Australian thorny devil lizard (Moloch horridus) (c) Wagler s pit viper (Tropidolaemus wagleri) (e) American alligator (Alligator mississippiensis) (d) Eastern box turtle (Terrapene carolina carolina) Aves Birds are archosaurs, but almost every feature of their reptilian anatomy has undergone modification in their adaptation to flight Birds are endothermic, capable of keeping the body warm through metabolism Highly adapted for flight The major adaptation is wings with keratin feathers Other adaptations include lack of a urinary bladder, females with only one ovary, small gonads, and loss of teeth Early feathers might have helped dinosaurs Gain lift when they jumped Gain traction running up hills Glide from trees By 150 million years ago, feathered theropods had evolved into birds Archaeopteryx remains the oldest bird known 11

12 Figure 34.30b (b) Bone structure Figure 34.30a Finger 1 Wing Forearm Wrist Palm Finger 2 Finger 3 Vane Shaft Shaft Barb Barbule Hook Feather structure Figure Toothed beak Wing claw Airfoil wing with contour feathers Long tail with many vertebrae 12

13 Living Birds Living birds belong to the clade Neornithes Several groups of birds are flightless The ratites, order Struthioniformes Penguins, order Sphenisciformes Certain species of rails, ducks, and pigeons 2011 Pearson Education, Inc. Figure Figure

14 Figure Mammalia class Mammalia, are represented by more than 5,300 species amniotes that have hair (fur) and produce milk Mammary glands, which produce milk Hair A high metabolic rate, due to endothermy A larger brain than other vertebrates of equivalent size Differentiated teeth Three Major Clades Monotremes are a small group of egglaying mammals consisting of echidnas and the platypus Marsupials: born very early in its development and completes its embryonic development while nursing in a maternal pouch called a marsupium Eutherians have a more complex placenta & complete their embryonic development within a uterus 14

15 Figure 34.38a 15

16 Figure 34.40a Marsupial mammals Plantigale Eutherian mammals Deer mouse Marsupial mole Mole Sugar glider Flying squirrel Figure 34.40b Marsupial mammals Wombat Eutherian mammals Woodchuck Tasmanian devil Wolverine Kangaroo Patagonian cavy 16

17 Eurasian Pygmy Shrew Sorex minutus Great Blue Whale Balaenoptera musculus Size Comparisons 17