Deuterostomes
Phylum Echinodermata Exclusively marine Deuterostomes with an endoskeleton Pentaradial symmetry Sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers 2
Micrognathozoa Rotifera Cycliophora Platyhelminthes Brachiopoda Bryozoa Annelida Mollusca Nemertea Loricifera Kinorhyncha Nematoda Tardigrada Arthropoda Onychophora Chaetognatha Echinodermata Chordata Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protostomes Platyzoa Spiralia Lophotrochozoa Ecdysozoa Deuterostomes 3
5 extant classes Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1. Asteroidea (sea stars and sea daisies) Important predators in many marine systems Most have 5 arms, some have multiples of 5 2. Echinoidea (sea urchins and sand dollars) Lack arms Double rows of tube feet Protective moveable spines a. Alex Kerstitch/Visuals Unlimited Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. c. Class: Asteroidea Class: Echinoidea 4 Daniel W. Gotshall/Visuals Unlimited
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Class: Ophiuroidea e. Jeff Rotman/Photo Researchers, Inc. 3. Ophiuroidea (brittle stars) Largest class Arms are equal diameter their entire length Arms are easily autotomized 5
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Class: Crinoidea Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Class: Holothuroidea d. Reinhard Dirscherl/Visuals Unlimited b. Randy Morse/GoldenStateImages.com 4. Crinoidea (sea lilies and feather stars) 5. Holothuroidea (sea cucumbers) 6
Symmetry Pentaradial as adult, bilateral as larva Oral surface defines mouth All systems organized with branches radiating from center Nervous system is nerve ring with branches No centralization of function Endoskeleton Epidermis covers endoskeleton Composed of calcium carbonate ossicles May be tightly or loosely joined All members have mutable collagenous tissue 7
Water-vascular system Radially organized Radial canal extends from ring canal into each body branch Water enters through madreporite Flows through stone canal to ring canal Tube feet may or may not have suckers Ampulla muscular sac at base Used in movement, feeding, gas exchange 8
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stomach Anus Skeletal plates Digestive glands Madreporite Water-vascular system b. Tube feet Gonad a. Radial canal Ampulla Tube feet b: Frederic Pacorel/Getty Images 9
Regeneration Many able to regenerate lost parts Some reproduce asexually by splitting Most reproduction is sexual Gonochoric Gametes released into water Free-swimming larvae Each class has a characteristic type of larva 10
Micrognathozoa Rotifera Cycliophora Platyhelminthes Brachiopoda Bryozoa Annelida Mollusca Nemertea Loricifera Kinorhyncha Nematoda Tardigrada Arthropoda Onychophora Chaetognatha Echinodermata Chordata Phylum Chordata Chordates are deuterostome coelomates Nearest relatives are echinoderms (the only other deuterostomes) Fishes, amphibians, reptiles, birds, and mammals Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protostomes Platyzoa Spiralia Lophotrochozoa Ecdysozoa Deuterostomes 11
1. Nerve cord 2. Notochord May be replaced by vertebral column 3. Pharyngeal slits Pharyngeal pouches present in all vertebrate embryos 4 Features Hollow dorsal nerve cord Pharyngeal pouches Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Notochord Postanal tail 4. Postanal tail 12
All chordates have all four of these characteristics at some time in their lives Other characteristics also distinguish chordates Chordate muscles are arranged in segmented blocks called somites Most chordates have an internal skeleton against which the muscles work Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 500 µm Eric N. Olson, Ph.D./The University of Texas MD Anderson Cancer Center 13
Fishes Most diverse vertebrate group Over half of all vertebrates Provided the evolutionary base for invasion of land by amphibians 14
Fishes have the following characteristics 1. Vertebral column Hagfish and lamprey exceptions 2. Jaws and paired appendages Hagfish and lamprey exceptions 3. Internal gills 4. Single-loop blood circulation 5. Nutritional deficiencies Inability has been inherited by all their vertebrate descendants 15
Mixini Cephalaspidomorphi Chondrichthyes Actinopterygii Sarcopterygii Amphibia Mammalia Chelonia Lepidosauria Crocodilia Aves Class Amphibia First vertebrates to walk on land Direct descendants of fishes Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 16
5 distinguishing amphibian features 1. Legs adaptation to life on land 2. Lungs 3. Cutaneous respiration supplement lungs 4. Pulmonary veins separate pulmonary circuit allows higher pressure blood to tissues 5. Partially divided heart improves separation of pulmonary and systemic circuits 17
Successful invasion of land by vertebrates required several adaptations Legs to support body s weight Lungs to extract oxygen from air Redesigned heart and circulatory system to drive larger muscles Reproduction still in water to prevent egg drying System to prevent whole body desiccation 18
Mixini Cephalaspidomorphi Chondrichthyes Actinopterygii Sarcopterygii Amphibia Mammalia Testudines Lepidosauria Crocodilia Aves Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Class Reptilia Over 7,000 living species All living reptiles exhibit three key features 1. Amniotic eggs, which are watertight 2. Dry skin, which covers body and prevents water loss 3. Thoracic breathing, which increases lung capacity 19
Modern reptiles developed two important characteristics Internal fertilization Sperm fertilizes egg before protective membranes are formed Improved circulation Oxygen is provided to the body more efficiently Septum in heart extended to create partial wall Crocodiles, birds, and mammals have completely divided 4-chambered heart 20
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Most Reptiles Lung capillaries Fish Gill capillaries Ventricle Right atrium Atrium Other capillaries a. b. Other capillaries 21
Mixini Cephalaspidomorphi Chondrichthyes Actinopterygii Sarcopterygii Amphibia Mammalia Testudines Lepidosauria Crocodilia Aves Class Aves Birds are the most diverse of all terrestrial vertebrates 28 orders, 166 families, about 8,600 species Success lies in unique structure feather Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 22
Birds still retain many reptilian traits Amniotic eggs and scales on legs Lack teeth and tails of reptiles Two major distinguishing traits Feathers Modified scales of keratin Provide lift for flight and conserve heat Flight skeleton Bones are thin and hollow Many are fused for rigidity anchor strong flight muscles 23
Adaptations for flight 1. Efficient respiration Air passes all the way through lungs in a single direction 2. Efficient circulation 4-chambered heart so muscles receive fully oxygenated blood Rapid heartbeat 3. Endothermy Body temperature (40 42 o C) permits higher metabolic rate 24
Mixini Cephalaspidomorphi Chondrichthyes Actinopterygii Sarcopterygii Amphibia Mammalia Testudines Lepidosauria Crocodilia Aves Class Mammalia There are about 4,500 species of mammals Lowest number among 5 vertebrate classes 3200 species are rodents, bats, shrews, or moles Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 25
2 fundamentally mammalian traits 1. Hair Long, keratin-rich filaments that extend from hair follicles Insulation, camouflage, sensory structure 2. Mammary glands Females possess mammary glands that secrete milk 26
Other notable features of mammals Endothermy depends on higher metabolic rate 4-chambered heart Respiration using diaphragm Placenta in most mammals Specialized organ that brings fetal and maternal blood into close contact 27
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Uterus Chorion Umbilical cord Placenta Yolk sac Amnion Fetus 28
Early Hominids Genus Homo 3 7 species (depending) Genus Australopithecus 7 species Older and smaller-brained Several even older lineages In every case where the fossils allow a determination, the hominids are bipedal, the hallmark of hominid evolution 29
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Australopithecus afarensis Australopithecus robustus Homo habilis Homo floresiensis Homo sapiens sapiens Homo sapiens sapiens Homo neanderthalensis Homo heidelbergensis Homo floresiensis Homo erectus Homo ergaster Homo habilis Australopithecus africanus Australopithecus afarensis Australopithecus anamensis Ardipithecus ramidus Australopithecus boisei Sahelanthropus tchadensis Australopithecus robustus 7.5 7 6.5 6 5.5 5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 Millions of Years Ago (MYA) 30
Australopithecines Our knowledge is based on hundreds of fossils found in Africa Characteristics Weighed about 18 kg About 1 m tall Hominid dentition Brains no larger than those of apes Walked upright 31
Bipedalism Seems to have evolved as australopithecines left forests for grasslands and open woodland African fossils demonstrate that bipedalism extended back 4 MYA Substantial brain expansion, on the other hand, did not appear until about 2 MYA Why bipedalism evolved is still a matter of controversy 32
Genus Homo The first humans evolved from australopithecine ancestors about 2 MYA Thought to be Australopithecus afarensis In the 1960s, hominid bones were found near stone tools in Africa Early human was called Homo habilis It closely resembled Australopithecus, but had larger brain 33
Homo floresiensis In 2004, a new human species was discovered in the tiny Indonesian Island of Flores Youngest fossils only 15,000 years old! H. floresiensis had a diminutive stature Coexisted with and preyed on a miniature species of elephant (now extinct) Believed to be more closely related to H. erectus than to H. sapiens 34
Small size may be an example of island dwarfism 35
Modern Humans Modern humans first appeared in Africa about 600,000 years ago Three species are thought to have evolved Homo heidelbergensis (oldest) Coexisted with H. erectus Homo neanderthalensis Shorter and stockier than modern humans Homo sapiens ( wise man ) Some lump all 3 into H. sapiens 36
Neanderthals, Homo neanderthalensis Made diverse tools Took care of sick and buried dead First evidence of symbolic thinking They abruptly disappeared about 34,000 years ago Suddenly replaced by Cro-Magnons 2 species did not interbreed Complex social organization Elaborate cave paintings Thought to have had full language capabilities 37
Cro-Magnon art 38
Homo sapiens Only surviving hominid Progressive increase in brain size Effective making and use of tools Refined and extended conceptual thought Use of symbolic language Extensive cultural experience We change and mold our world rather than change evolutionarily in response to the environment 39