BIO 104 Dr Bej 04 07 2014 Earthworms tract Polychaetes Eat their way through soil extracting nutrients as the soil passes through the digestive Undigested material mixed with mucus is eliminated as castings through the anus Earthworms till the earth and castings improve soil texture Sandworm fan worm Have segmented appendages that function in movement and as gills Segmented appendages with hard bristles help them wriggle about snd also increase surface area for respiration Mostly marine crawl burrow in the sea floor Leeches Some are free living carnivores eat small invertebrates such as snails and insects Some suck blood Most live in freshwater some are terrestrial that inhabit moist vegetation in the tropics Phylum Arthropoda Jointed appendages 1 billion billion 10 18 150 million arthropods per person Over 1 mil Sp Mostly insects 2 out of 3 sp Are arthropods Most successful animal phylum All habitats Segmented segments plus appendages specialized for function Division of labor among body regions annelids repeated similar segments Body is complex covered with o Exoskeleton made of protein and chitin Thick and protective on the head Thin and flexible in the joints Used for protection provides for a point of attachment for muscles Molted during growth Types o Arachnids Scorpions spiders ticks and mites 4 pairs of walking legs Land dwelling Specialized pair of feeding appendages Spiders have fangs and poison glands They immobilize prey with their fangs Then they inject digestive juices into the wound and eat the liquid meal o Crustaceans Crabs lobsters crayfish shrimp and barnacles Aquatic Multiple pairs of specialized appendages Grass shrimp known as popcorn shrimp and translucent and feed on algae Barnacles sometimes confused with bivalve mollusks are sessile exoskeleton hardened into shells with calcium carbonate Jointed appendages are projected from the shell to catch plankton o Millipedes and centipedes Have similar segments over most of the body but have jointed appendages Millipedes eat decaying plant matter 2 pairs of legs per segment Centipedes are carnivorous have a pair of poison claws used in defense and to paralyze prey Each segment has a pair of long legs Some of the oldest insect fossils are dated to be 400 mil yrs old Insects Body o Head pair of sensory antennae pair of eyes and several mouth parts o Thorax 3 pairs of legs 1 or 2 pairs of wings o Abdomen o Wings are extensions of the exoskeleton and are not true appendages o Still have 3 pairs of walking legs Metamorphosis o Grasshoppers young resembles adults with different proportions by going through a series of molts o Larva Pupa Adult o Larva o Pupa Eats and grows after several molts Encased in a cocoon Larval organs break down and adult organs start to form from cells that were dormant in the Larva o Adult Emerges from the cocoon Insects have faster generation times which allows them to mutate quickly Mollusks Soft bodies with hard shells Radula straplike rasping organ used for feeding Body Plan 150 000 sp Mostly marine some freshwater some land dwelling o Muscular foot o Visceral mass contains most of the internal organs o Mantle fold of tissue drapes over visceral mass secretes shell Classification o Gastropods single spiraled shell into which animals retreat when threatened Distinct head with eyes at the tips of tentacles Snails and slugs o Bivalves clams oysters mussels scallops Shell divided into 2 halves Sedentary live in sand or mud in marine and freshwater environments o Cephalopods Built for speed and agility Squids and octopuses Few have large heavy shells most have small internal shells squids and octopuses have no shell Posses large brain and sophisticated sense organs Use beak like jaw and radula to crush prey Mouth is at base of foot and is drawn out into several long tentacles for catching prey o Polyplacophora Chiton Echinoderms Sea urchins sea stars sand dollars and sea cucumbers Spiny surface marine sessile or slow moving no body segments most have radial symmetry have an endoskeleton made up of hard plates just below skin bumbs and spikes of the endoskeleton make up the prickly surface Posses a Water Vascular System o Which is a network of canals that circulate water throughout the body for gas exchange and waste disposal Branches into extensions called tubefeet suction cup like appendages that are used for moving and gripping prey Share an evolutionary branch with vertebrates Embryology and coelom formation differs from other invertebrates