Arthropods, from last time Crustacea are the dominant marine arthropods Crustacea are the dominant marine arthropods any terrestrial crustaceans? Should we call them shellfish? sowbugs 2 3 Crustacea Morphology - each segment of thorax and abdomen usually has an appendage - appendages may be branched Uniramia - one branch (unbranched appendages) Includes insects, millipedes, centipedes 4 5 The insects in particular... The insects in particular - three body sections 6 7
The insects in particular - three body sections head, thorax, abdomen The insects in particular - three body sections head, thorax, abdomen - six legs 8 9 The insects in particular - three body sections head, thorax, abdomen - six legs - comprise most of the animal species on the planet 10 Diversity of all described species of animals ANTS, BEES & WASPS B FLIES & MOTHS BEETLES FLIES TRUE BUGS INSECTS ARTHROPODS CHORDATA PHYLA 73 % INSECTS 12 % ARTHROPODS 4 % CHORDATES 11 % ALL PHYLA 11 Insect species Described species of vertebrates - 38,000 Described species of insects - 875,00 And the rate of discoveries of new insect species suggests that there are many undescribed - estimates of 2 million to 30 million Even the most conservative estimate suggests that most insect species have not been described! 12 Why have insects been so evolutionarily successful? i. Small size - habitat becomes more complex as you become smaller, allows more subdivision 13
Why have insects been so evolutionarily successful? Diversity of all described species of animals i. Small size - habitat becomes more complex as you become smaller, allows more subdivision ii. Flight - more movement and rapid colonization of plants ANTS, BEES & WASPS B FLIES & MOTHS BEETLES FLIES INSECTS ARTHROPODS CHORDATA PHYLA What do these insect groups have in common? BUGS 14 15 Why have insects been so evolutionarily successful? i. Small size - habitat becomes more complex as you become smaller, allows more subdivision ii. Flight - more movement and rapid colonization of plants iii. Complete metamorphosis - change in body plan iii. Complete metamorphosis - change in body plan allows specialization of immatures for feeding and growth, of adults for dispersal and reproduction 16 17 Why have insects been so evolutionarily successful? i. Small size - habitat becomes more complex as you become smaller, allows more subdivision ii. Flight - more movement and rapid colonization of plants iii. Complete metamorphosis - change in body plan Animal diversity 4 - The Deuterostomes (Echinodermata, Chordata) Key concepts Key morphological characters of the Echinodermata, Chordata Distinguish lineages of vertebrates: Three lineages of fishes (jawless fishes, cartilaginous fishes, bony fishes) and three lineages of terrestrial vertebrates (amphibians, reptiles [including birds] and mammals) Distinguish three groups of mammals Secondary evolution of ocean dwelling for terrestrial animals: the marine mammals 18 18a
The Echinodermata Examples? Sea stars, sea urchins, sea cucumbers, sand dollars The Echinodermata: Sea stars, sea urchins, 19 20 The Echinodermata: Sea cucumbers The Echinodermata: Sand dollars, brittle stars 21 22 The Echinodermata Morphology Pentameric symmetry as adults - rays or arms arranged in groups of 5 (but planktonic larvae bilaterally symmetrical) Endoskeleton of interlocking calcium carbonate plates covered by epidermis Water-filled canal system leads to tube feet for moving or manipulating things - feet can be extended or retracted with water pressure 23 The Echinodermata Feeding Predacious (sea stars) or grazers (sea urchins) or filter feeders (sea cucumbers, others) Favorite food of sea stars is bivalves like clams and mussels - how do they eat them? 24
The Echinodermata Feeding How do sea stars eat bivalves? Anchor themselves, both sides of shell with tube feet, exert constant pressure, wear out the muscles of the bivalve. Then... The Echinodermata Feeding How do sea stars eat bivalves? Then, the sea star everts its mouthparts and stomach into the crack, consumes the contents! Tube feet After dinner - everted stomach, and empty shell 25 26 Last, but hardly least, the Chordata Chordates = Vertebrates + two small groups - the Tunicates and the Lancelates The Chordata Tunicates As adults look like sponges! But larvae have all the defining features of chordates What feature in particular? Lancelate 27 28 The Chordata Morphology - dorsal hollow nerve cord - notochord (a flexible rod, supporting the nerve cord) for at least part of life In vertebrates the notochord disappears early in development, and is replaced by the vertebral column that surrounds the nerve cord Lancelet 29 30
The general vertebrate body plan The general vertebrate body plan Dorsal nervous system Dorsal nervous system Internal skeleton 31 32 The general vertebrate body plan The general vertebrate body plan Dorsal nervous system Internal skeleton Organs suspended in coelom Dorsal nervous system Internal skeleton Organs suspended in coelom Well developed circulatory system with heart 33 34 Evolution of vertebrates First vertebrates were likely mud-suckers similar in morphology to modern jawless fishes ingested mud, removed organic material osmoregulatory* abilities allowed fishes to exploit estuaries** Modern jawless fishes - Lampreys and hagfish Mouth of a lamprey *osmoregulatory: control of levels of solutes in cells (in this case salts) **estuaries: where salty ocean water and fresh water mix 35 Lamprey feeding 36
Second group of fishes - the cartilaginous fishes Examples? Second (?) group of fishes - the cartilaginous fishes So named because skeleton made from cartilage First real jaws? (some have JAWS) 37 38 Third group of fishes - the bony fishes Cartilage replaced by bony skeleton Third group of fishes - the bony fishes Most fish are bony fish 39 40 Third group of fishes - the bony fishes evolved lunglike sacs for respiration, became modified into swim bladders What are swim bladders used for? Amphibians - the first vertebrates on land 41 42
Amphibians - the first vertebrates on land But - confined to moist habitats: 1) Respire with lungs and across moist skin 2) Reproduce in the water, have external fertilization 3) Eggs not waterproof - generally have to be laid in water (video segment showing exceptions!) Reptiles - better adapted to dry land 1) skin covered with scales 2) Internal fertilization 3) Egg with waterproof shell - the Amniotes 43 44 One hypothesis for terrestrial vertebrate phylogeny The reptiles AMNIOTES REPTILES MAMMALS TURTLES TUATARAS AMNIOTES REPTILES MAMMALS TURTLES TUATARAS LIZARDS & SNAKES LIZARDS & SNAKES CROCODILIANS CROCODILIANS DINOSAURS AND BIRDS DINOSAURS (INCL. BIRDS) A tuatara - single species remaining of this reptile lineage AMPHIBIANS 45 AMPHIBIANS Birds are reptiles and closely related to dinosaurs: scales have been modified into feathers 46 REPTILES Mammalia I. What unites us? Hair, milk producing glands 47 48
Mammalia i. What unites us? Hair, milk producing (mammary) glands ii. Not many species (4,500 compared to 875,000 species of insects) Mammalia i. What unites us? Hair, milk producing glands ii. Not many species (4,500 compared to 875,000 species of insects) Iii. But very diverse morphologically, ecologically 2 g 160,000 kg 49 50 Mammalia i. What unites us? Hair, milk producing glands ii. Not many species (4,500 compared to 875,000 species of insects) iii. But very diverse morphologically, ecologically iii. And our species has the greatest impact of any animal on life on this planet Mammalia Three commonly distinguished groups of mammals Monotremes - egg laying mammals with reptilian-like splayed legs. Only 3 spp.: the Australian platypus and 2 spp. of echidna Marsupials - give birth to tiny young, nursed in ventral pouch - most of 240 spp. in Australia Eutherian mammals - (= placental mammals ) by far the most diverse - over 4,000 spp. 51 52 Monotremes - egg laying mammals Marsupials - mammals with pouches Platypus Echidna 53 54
Eutherian mammals - the rest of us Evolution of Cetacea (whales, porpoises and dolphins) 55 56 Evolution of Cetacea (whales, porpoises and dolphins) How did land mammals adapt to the sea? Entire transition from land mammal to marine whale - only 8 million years. Secondary evolution of ocean dwelling in animals Secondary evolution - reacquisition of a lost trait New fossils show the closest land-living relatives to whales are the artiodactyls (includes hippos, pigs, camels giraffes, deer, sheep and cattle) 57 Evolution of Cetacea (whales, porpoises and dolphins) Likely evolutionary sequence Lived on land - fed while wading A later group Reconstruction of the first cetacean were more like crocodiles - ambushed prey in shallow water 58 Evolution of Cetacea (whales, porpoises and dolphins) A later marine group had a very long snake-like body, a tail-fluke and complete, tiny hind-limbs with mobile knee and toes Evolution of Cetacea (whales, porpoises and dolphins) Modern Cetacea - nearly 80 species Hind limb 59 Forelimbs modified to form flippers Nostrils on top of the head - blowhole Hind limbs do not extend out of body 60