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Flashcards in lecture 14 Deck (30):

using body plans to build phylogenetic trees

-far left is the ancesteral colonial protist
-eumetazoans: animals with true tissues
-sponges: have mo true tissues
-animals with radial symmetry vs animals with bilateral symmetry
-most animals have bilateral symmetry-bilaterians
-further divided into two clades on the basis of embryology
-deuterostomes and protosomes



-stationary animals
-most marine, some fresh water
-some are radially symmetrical
-most lack body symmetry
-resemble thick walled sec with holes
-water is drawn through the pores into a central cavity which then flows out through a larger opening
-more complex sponges have branching water canals


sponge body consists of two cell layers

-which are seperated by a gelatinous region
-inner layer of flagellated cells choanocytes help sweep water through the sponges body
-amoebocytes wander through the middle body region
-produce supportive skeletal fibers composed of flexible protein called spongin and mineralized particles called spicules
-sharp spicules may also protect the large opening


how do sponges feed?

-sponges are suspension feeders
-animals that collect food particles from the water
-the food is passed through some sort of food-trapping equipment
-feed by collecting food particles from water that stream through their pores
-chanocytes trap food particles in mucus on membranes that surround the base of their flagella and then engulf the food by phagocytosis
-the amoebocytes pick up food packaged in food vacuoles from choanocytes and digest it carrying the nurtients to the other cells


adult sponges

-adult sponges are sessile (anchored in place)
-they are unable to escape predators
-consequently sponges produce defensive compounds such as antibiotics and toxins to deter pathogens, parasites and predators
-the simplest of all of the animals
-no nerve or muscles
-individual cells can sense and react to environmental changes
-no true tissues
-thought to have evolved from flagellated protist ancestor



-eumatozoan: have true tissues
-these are one of the oldest groups within the emumatozoa
-includes: hydras, jellyfish, and corals
-radial symmetry
-only two tissue layers
-outer epidermis and inner cell layer that lines the digestive cavity
-jelly-filled-middle region which may contain scattered amoebid cells
-have contractile tissues and nerves in their simplest form
-incomplete gut or gastrointestinal cavity
-mouth and no anus: single opening
-tentacles surround the mouth opening to assist the trapping and intake of food


there are two main body forms within the group cnidarians

-some species occur in only one form where as others exist in both forms during the life cycle
1. medusa
-mouth facing downwards
-organism is umbrella shaped with a thick middle layer
composed of a viscous jelly-like material
ex) jellyfish
2. polyp
-tentacles face up
-colonial aggregations are the most common
ex) sea anemone



-unique stinging cells
-function in defense and prey capture
-the prey is paralyzed by toxin released during the sting
-cnidocytes are found throughout the epidermis and tentacles
-nearly all cnidaria are carnivorous
-feeding predominately on small crustateans and other plankton that is captured by the tentacles
-prey enters the gastrointestinal cavity via the mouth where digestion takes place using extracellular enzymes



-flat worms
-bilateral symmetry
-thin and ribbon like
-simplest of the bilateral
-marine, freshwater, and damp habitats
-one opening to the gastrointestinal cavity
-GI cavity contains fine branches distributing food throughout the animal


platyhelminthes: planarians

-free living flat worms
-head with a pair of light sensitive eyespots
-flap at each side of the head to detect chemicals
-dense packs of nerve cells function as a brain
-a pair of nerve cords connect with small nerves that branch throughout the body
-live on undersurfaces of rocks in steams and freshwater ponds
-highly branched GI cavity
-sucks food in from the mouth at the tip of a muscular tube
-use cilia on their ventral surface to crawl in search of food
-also have muscles that enable them to twist and turn


platyhelminthes: flukes

-have tough protective covering
-suckers that attach to their host
-reproductive organs occupy almost the entire interior of these worms
-complex life cycles
-intermediate hosts in which larva develop
-larva infect final host where they will live as adults
-ex) blood flukes that cause schisosmiasis in humans spend a part of their life cycle in snails


platyhelminthes: tapeworms

-inhibit the digestive tract of vertebrates as adults
-ribbon like body
-this is the most evolutionary advanced of all of the flatworms
-lacks a gut
-nutrients are taken up from the host across the wall of the worm body
-the nervous system is also reduced



-these are cylindrical worms with a blunt head and a tapered tail
-they are covered by a tough, non-living cuticle
-periodically shed
-used as protection and to resist dehydration
-complete digestive tract
-a mouth and an anus
-soil dwelling
-body is composed of a fixed cell number
-some are parasitic
-big agricultural pests, attack animal and plant roots
-some cause animal diseases such as heartworm



-most diverse group of invertebrates
-terrestrial, marine, and fresh water organisms
-have seperate sexes
-bilateral symmetry
-3 tissue layers
-body is composed of a small, not well defined head, large dorsal visceral mass and a broad, flat ventral foot
-visceral mass covered by the mantle which secretes the shell
-shell is unique character of the molluscs
-shell is composed of calcium carbonate
-contains gills for respiration
-have a true coelom
-have a circulatory system
-feed with a structure called radula
-life cycle includes a ciliated larval stage called a trochophore


molluscs three major classes

1. gastropods
2. bivalves
3. cephalopods


molluscs: gastropods

-include snails and slugs
-largest and most diverse class
-marine, freshwater and terrestrial
-the only molluscs that live on land
-have a single, spiraled shell where the animal can retreat when threatened
-distinct head with eyes at tentacle tips
-terrestrial molluscs lack gills found in aquatic molluscs
-the lining of the mantle cavity instead functions as a lung preforming gas exchange with the air


molluscs: bivalves

-clams, oysters and muscles
-shells divided into two halves and hinged together
-most are suspensions feeders
-gills in the mantle cavity used for feeding and gas exchange
-mucus-coated gills trap small food particle from the water
-cilia sweeps particles to the mouth
-sedentary, living in sand or mud
-muscular foot is used for digging and anchoring


molluscs: cephalopods

-squid, octopus
-adapted to lifestyle of fast agile predators
-use beak-like jaws and radula to crush/rip prey apart
-mouth is at the base of the foot
-drawn into several long tentacles to catch and hold prey
-marine and most free swimming
-swim via a water jet propulsion from the mantle cavity
-highly developed nervous and locomotion systems
-change color in response to threat
-octopus is considered the most intelligent invertebrate



-segmented body composed of a number of sections
-segmentation allows added mobility for swimming and burrowing
-marine, freshwater and terrestrial
-suspension feeders, scavenging, herbivores and carnivores
-used as an indirect source of food
-ex) fish bait
-medicinal leeches promote healing of tissue grafts and re-attached appendages


three major annelid groups

1. polychaeta
2. earthworms
3. leeches


three major platyhelminthes groups

1. planarians: free living flat worms
2. flukes: parasitic
3. tapeworms: parasitic


annelids: polychaeta

-largest group
-paddle-like parapodia function as gills and assist in locomotion
-one on each appendage
-very diverse in terms of lifestyle, function, and form
-secrete and occupy tubes
-search for prey on the sea floor or live within tubes and filter particles
-extend appendages coated in mucus to trap suspended food particles
-marine, burrow, bottom dwellers, live in rocks and shells and can swim when necessary


annelids: earthworms

-may body structures are repeated in each segment
-digestive tract is continuous through worm body
-nervous system includes brain and ventral nerve cord
-nerve cell cluster in each segment
-segment have longitudinal and circular muscles
-each segment has bristles that offer traction
-closed circulatory system
-do not self-fertilize


annelids: leeches

-dorso-ventrally flattened
-ventral and posterior suckers
-parasitic, thriving off of host blood
-free-living, carnivorous species as well
-eat small invertebrates such as snails
-fresh water, marine, and terrestrial
-razor-like jaws split animal skin
-leech secretes anticoagulant and anesthetic into the wound to prevent pain and blood clotting



-the largest group of animals
-exoskeletons made out of chitin
-it grows and molts its exoskeleton in a process called ecdysis
-jointed appendages modified for many different functions
-open circulatory system
-fluid filled with hemolymph that circulates into spaces surrounding tissues and organs
-variety of specialized organs for gas- exchange


arthropods: chelicerates

-named for claw-like feeding appendages called chelicerae
-most marine forms are extinct
-the horseshoe crab still exists today
-most modern forms are arachnids: a group that includes spiders, ticks, mites and scorpions


arthopods: millipedes and centipedes

-millipedes: have a large number of legs
-each trunk segment has two pair of legs
-centipedes: carnivores
-contain jaw-like mandibles
-one pair of legs per trunk segment


arthropods: crustaceans

-usually have branched appendages
-specialized for feeding and locomotion
-nearly all aquatic
-include lobster and cray fish and barnacles
-barnacles contain a hardened shell containing calcium carbonate
-jointed appendages project from the shell to strain food from water
-anchor themselves to objects such as boats using adhesive that they produce that is stronger than any glue ever invented



-insects are the most mumerous
-most successful
-consist of three body parts: head, thorax, and abdomen
1. head: sensory antenna and eyes, various mouth parts
2. thorax: three sets legs, wings (not all insects have wings)
3. abdomen
ex) grasshopper, beeties, and moths
-many insects have developmental processes that follow incomplete metamorphosis:
-transition from larva to adult goes through many molts without forming a pupa
-complete metamorphosis: -larvae specialized for eating and growing
-larvae look very different from adults
-adults specialized fro dispersal and reproduction



-phylum echinodermata includes organisms such as sea stars, sand dollars, and sea urchins
-all marine
-radially symmetrical as adults
-bilateral larvae
-endoskeleton: spines and plates found internally
-slow moving or sessile
-mouth located on underside (ventral)
-tube feet are used to respiration, locomotion, and feeding
-a thin bumpy or spiny skin covers an endoskeleton of hard calcareous plates