Requirements for Animal Life Animal phylogeny based on sequencing of SSU-rRNA The demands of 3 unique environments Marine, freshwater, terrestrial Gas exchange Nutrition Distribution and transport Disposal of cellular wastes Internal water and salt balance Reproduction and development Support and movement Phylum Bryozoa Ectoprocta 4000 species, both FW and Marine Colonial- Zoecium Jack-in-the-box operculum Colonial Bryozoans A lophophore is a structure used for: A. Reproduction B. Feeding C. Gas Exchange D. A and B E. B and C 1
Animal phylogeny based on sequencing of SSU-rRNA Phylum Mollusca: snails, slugs, chitons, clams, octopus and squid Trend toward rounder body: low SA/vol ratio Lack of segmentation (except Neopilina) Class Gastropoda: snails, slugs, limpets Largest molluscan class, 40,000 species Mobile: Herbivores and Carnivores 3 important changes from ancestral mollusc Greater cephalization: affects sensory and locomotion Asymmetrical spiral shell: portable protection Torsion: realignment of body with shell Feeding strategies and specializations Gills or lungs Generic Snail Radula Radular membrane Odontophore Radular teeth 2
Torsion- do you see a problem? (and de-torsion) Class Polyplacophora: chitons 600 living species, mostly intertidal Most similar to ancestral mollusc Broad-footed herbivores 8 overlapping plates Very little cephalization: no eyes or tentacles, small head w/ radula Cryptochiton stelleri- Gumboot Chiton Class Bivalvia: clams Clam Laterally compressed w/dorsal hinge Very large mantle cavity: use of gills for respiration and suspension (filter) feeding Incurrent and excurrent siphons No radula or distinct head present Pearls: require inner nacreous layer 3
Feeding Water/Food path Locomotion Cl. Cephalopoda: nautilus, squid, octopus 650 species, extinct members include Ammonites (65 mya) Predators Swimming lifestyle: jet propulsion Reduced or absent shell Closed circulatory system Cephalization: sensory, movement, learning Foot gives rise to tentacles (arms) Direct development (larvae?) Cephalopod eye: convergence 4
Cephalopoda Giant Squids Dorsal Anterior Ventral Posterior Architeuthis Dosidicus gigas- Humboldt Squid 5
A trochophore larva Which of the following Molluscan class does not have a radula? A. Bivalvia B. Cephalopoda C. Gastropoda D. Polyplacophora E. None, they all have a radula Requirements for Animal Life Animal phylogeny based on sequencing of SSU-rRNA The demands of 3 unique environments Marine, freshwater, terrestrial Gas exchange Nutrition Distribution and transport Disposal of cellular wastes Internal water and salt balance Reproduction and development Support and movement Annelida- the segmented worms Phylum Annelida: ringed worms Subdivided coelom w/ hydrostatic skeleton Segments = metameres Segmental specialization and independence Locomotion (w/ hydrostatic skeleton) Other advantages? Setae made of chitin Closed circ system w/ specializations Cephalization- different segments Hermaphrodites: clitellum 6
Class Polychaeta: segmented marine worms About 5000 species Most live in burrows or tubes Increased cephalization Parapodia: locomotion, respiration, feeding Trochophore larvae Possible ancestors of Arthropods Polychaete reproduction Atoke Trochophore larva Apical tuft Stomach Mouth Ciliary band Anus Epitoke 7
Requirements for Animal Life Animal phylogeny based on sequencing of SSU-rRNA The demands of 3 unique environments Marine, freshwater, terrestrial Gas exchange Nutrition Distribution and transport Disposal of cellular wastes Internal water and salt balance Reproduction and development Support and movement Phylum Nematoda Freeliving and parasitic pseudocoelmates Body structure: high SA:vol Complete digestive tract Separate sexes Cuticle C. elegans: an experimental model Parasites: Ascaris lumbricoides - The Large Human Roundworm 1.5 Billon infected 64% of southeast US 200K eggs/day Animal phylogeny based on sequencing of SSU-rRNA Phylum Arthropoda: jointed foot Evolutionary Trends 1. Specialization of segments 2. Loss or fusion of body segments (tagmata) 3. Increased cephalization Unique Arthropod Features 1. Jointed appendages- Legs!! 2. Exoskeleton 3. Ecdysis (molting) and hormonal control 4. Open circulatory system 5. Gills, book lungs or trachael tubes 6. Tracheal system 8
Molting- Ecdysis Problem- How grow in an armored suit? Hormonal control Re-absorption of old inner cuticle New soft cuticle formed Old shell left behind Class Pycnogonida Sea Spiders Long, thin legs and body Proboscis mouth for sucking Male parental care of eggs and young Class Ostracoda Subphylum Crustacea: Mostly marine but some terrestrial members Decapods - lobsters, crabs, shrimp Isopods - sow bugs and pill bugs Amphipods- beach jumpers Copepods planktonic Euphausids- krill Barnacles - sessile crustaceans Green Gland 9
Class Maxillopoda- Copepods Naupliar eye Antenna Ovary Ovisac Zooplankton-Copepod Lifecycle Barnacles Filter Feeders Highly modified body 1 st antenna Barnacle sex 2 nd antenna Naupliar eye Mandible Class Malacostraca Isopods Largest class of crustaceans Most common orders: Isopoda- dorsoventral flattened Amphipoda- laterally flattened Euphausia- Krill Decapoda- crabs and shrimp 10
Pelagic isopods Amphipods Euphausia Decapods Decapods 11
Requirements for Animal Life Animal phylogeny based on sequencing of SSU-rRNA The demands of 3 unique environments Marine, freshwater, terrestrial Gas exchange Nutrition Distribution and transport Disposal of cellular wastes Internal water and salt balance Reproduction and development Support and movement Phylum Chaetognatha Phylum Echinodermata: spiny skin - sea stars, brittle stars, sea cucumbers, sea lilies, urchins- General Features Exclusively marine Benthic herbivores or detritovores; in all habitats/depths Bilateral larvae, radial adult Endoskeleton Non-centralized nervous system Water-vascular system Non-segmented Well developed digestive system Cutaneous respiration Regenerative Capacity 5 Echinoderm Classes Figure 33.38 Anatomy of a sea star Cl. Ophiuroidea Cl. Crinoidea Cl. Asteroidea Cl. Echinoidea Cl. Holothuroidea 12
Tube feet movie Aristotle s lantern Holothuroidea Crinoidea 13
Which of the following is most important in the water vascular system? A. Hydrostatic skeleton B. Muscles C. Mucus D. Tube feet E. Endoskeleton Requirements for Animal Life The demands of 3 unique environments Marine, freshwater, terrestrial Gas exchange Nutrition Distribution and transport Disposal of cellular wastes Internal water and salt balance Reproduction and development Support and movement Animal phylogeny based on sequencing of SSU-rRNA What is a Chordate? Five Distinctive characteristics 1. Notochord 2. Dorsal, hollow nerve cord 3. Pharyngeal pouches/slits 4. Endostyle/Thyroid gland 5. Postanal tail Phylum Chordata Subph. Urochordata: sea squirts, larvaeceans General features of tunicates Cellulose tunic Mouth opens into basket-like pharynx Pharyngeal gill slits The Wonderful World of Mucus! 14
Phylum Chordata Subphylum Urochordata Larvaceans Larvaceans Animal Salps What is the one thing you don t have? A. Notochord B. Endostyle/Thyroid gland C. Postanal tail D. Dorsal, hollow nerve cord E. Pharyngeal pouches/slits 15