ECOL 182R 1st Edition Lecture 13 Outline of Last Lecture I Overview II Evolution III Diversification IV Body plans A Different appendages V Different lineages Outline of Current Lecture I Deuterostomes II Echinoderms A Key lineages III Chordates IV Vertebrates V Primates Current Lecture The most species rich lineages are echinoderms and the vertebrate groups called ray finned fishes tetrapods Echinoderms have radial symmetry and a water vascular system All vertebrates have a skull and most have an exoskeleton made of cartilage or bone Diversification of echinoderms was triggered by the evolution of appendages called podia For vertebrates it was evolution of the jaw Deuterostomes Four phyla Echinodermata Hemichordata xenoturbellida chordata Are invertebrates besides chordata Chordata includes both vertebrates and invertebrates Echinoderms spiny skins are named for the spines spikes Larvae are bilaterally symmetrical but adults are radially symmetric Defined by the water vascular system a series of branching fluid filled tubes and chambers that forms a hydrostatic skeleton An important part of this system is tube feet which are elongated fluid filled structures Podia are sections of the tube feet that project outside the body and help w movement Have an endoskeleton a hard supportive structure inside the body What s a chordate The phylum Chordata is defined by four things Pharyngeal gill slits are openings into the throat A notochord is a supportive but flexible rod that runs the length of the body while the dorsal hollow nerve cord is a bundle of nerve cells running next to it A dorsal hollow nerve cord A muscular post anal tail Has three subphyla In urochordates or tunicates pharyngeal gill slits are in larvae and adults but the notochord dorsal hollow nerve cord and tail occur only in larvae Cephalochordates or lancelets are small mobile suspension feeders that look like fish In vertebrates the dorsal hollow nerve cord is elaborated into the spinal cord The pharyngeal pouches in embryos turn into gills in aquatic species but not terrestrial The vertebrate fossil record 440 MYA bone in exoskeleton enveloping the body 400 MYA first bony fish with jaws 365 MYA animals with limbs or tetrapods 345 MYA first animals with watertight eggs called amniotic eggs Tetrapods First vertebrates that could reproduce on land Three major evolutionary innovations gave tetrapods this ability Amniotic egg has a watertight shell case enclosing a membrane bound food and water supply and waste repository Placenta where the amniotic egg is inside the female Elaboration of parental care encompasses any action of parents that improves ability of offspring to survive Among animals mammals and bird give the most extensive parental care Female mammals lactate they make milk With the combo of the placenta lactation placental mammals make the most extensive investment of time energy in offspring Key lineages Echinodermata Bilateral sym in larva radial sym in adults All have water vascular system with tube feet and produce and internal endoskeleton Five major lineages Feather stars sea lilies Sea stars basket stars Sea urchins and sand dollars Sea cucumbers Asteroidea Sea stars 1700 species Five or more arms radiating from central region that contains mouth stomach and anus Sexual reproduction Sexes are separate Echinoidea sea urchins sand dollars 800 species Most are herbivores Sand dollars use their mucus covered podia to collect food Most have a unique jaw like feeding thing made of five calcium carbonate teeth attached to muscles Sexual reproduction Sexes are separate Key lineages Chordata All have pharyngeal gill slits a notochord a dorsal hollow nerve cord and a post anal tail Three subphyla Urochordates Cephalochordates and Craniata vertebrates Urochordata tunicates 1600 species of tunicates or sea squirts all found in ocean Exoskeleton like coat called a tunic a U shaped gut and two siphons Suspension feeders Larvae swim with notochord Adults float or are sessile Cephalochordata lancelets 24 species all in marine sands Look like fish but actually have a lot of characteristics in between vertebrates and invertebrates A notochord that is retained in adults functions as an endoskeleton and helps w movement Craniates Lineages with skulls Are vertebrates are craniates but hagfish and lampreys are craniates but not vertebrates Hagfish lack a vertebral column but lampreys have small pieces of cartilage Vertebrata Chondrichthyes Sharks rays skates 970 species distinguished by their cartilaginous skeleton their jaws and their paired fins Most are marine a few freshwater Sharks use internal fertilization and fertilized eggs may be shed into water or retained until young are hatched Some sharks are viviparous lay egg and keep it in you it swims out of you as are rays Skates are oviparous lay egg and put it out there Vertebrata Actinopterygii ray finned fishes 27 000 species Have fins supported by long bony rods in a ray pattern 96 are teleosts the most important lineage Most ancient living vertebrates that have skeleton made of bone Avoid sinking with gas filled swim bladder Vertebrata Coelacanths Lungfish Independent lineages grouped together as lobe finned fishes Common diverse of the Devonian period but only 8 species today Important link between ray finned and tetrapods Their fleshy lobe shaped fins are supported by a linear arrangement of bones and muscles like tetrapods Vertebrata Amphibia frogs salamanders caecilians The most ancient tetrapods 5500 species found in ponds lakes or moist land Gas exchange through their skin Adults are carnivores but lay eggs in water or really moist areas Chordata Mammalia mammals They re endotherms regulate body temps internally Have hair fur to insulate body Have mammary glands for lactation Monophyletic class with three subclasses Monotremata most ancient group of mammals today Only 3 species They lay eggs have slow metabolisms Platypuses feed on small animals in streams echidnas feed on ants and termites Marsupials 275 known species Females have a placenta but young are born poorly developed after a short embryonic period Develop while attached to mother s nipple sucking milk Stay attached until big enough to move alone Eutheria placental animals 4300 species is the most species rich and diverse Grouped into 18 lineages or orders Young are way better developed at birth than marsupials Internal fertilization viviparous Reptilia turtles snakes lizards crocodiles birds