lecture 14 Flashcards
1
Q
using body plans to build phylogenetic trees
A
- 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
2
Q
sponges
A
- stationary animals
- sedentary
- 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
3
Q
sponge body consists of two cell layers
A
- 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
4
Q
how do sponges feed?
A
- 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
5
Q
adult sponges
A
- 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
6
Q
cnidarians
A
- 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
7
Q
there are two main body forms within the group cnidarians
A
-some species occur in only one form where as others exist in both forms during the life cycle
1. medusa
-motile’-swimming
-mouth facing downwards
-organism is umbrella shaped with a thick middle layer
composed of a viscous jelly-like material
ex) jellyfish
2. polyp
-stationary
-tubular
-tentacles face up
-colonial aggregations are the most common
ex) sea anemone
8
Q
cnidocytes
A
- 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
9
Q
platyhelminthes
A
- 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
10
Q
platyhelminthes: planarians
A
- 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
11
Q
platyhelminthes: flukes
A
- parasitic
- 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
12
Q
platyhelminthes: tapeworms
A
- 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
13
Q
nematodes
A
- roundworms
- 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
- pseudocoelomates
- complete digestive tract
- a mouth and an anus
- free-living
- 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
14
Q
molluscs
A
- 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
15
Q
molluscs three major classes
A
- gastropods
- bivalves
- cephalopods
16
Q
molluscs: gastropods
A
- 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
17
Q
molluscs: bivalves
A
- 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
18
Q
molluscs: cephalopods
A
- 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
- carnivorous
- 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
19
Q
annelids
A
- 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
20
Q
three major annelid groups
A
- polychaeta
- earthworms
- leeches
21
Q
three major platyhelminthes groups
A
- planarians: free living flat worms
- flukes: parasitic
- tapeworms: parasitic
22
Q
annelids: polychaeta
A
- 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
23
Q
annelids: earthworms
A
- 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
- hermaphrodites
- do not self-fertilize
24
Q
annelids: leeches
A
- 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
25
Q
arthropoda
A
- the largest group of animals
- segmented
- 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
26
Q
arthropods: chelicerates
A
- 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
27
Q
arthopods: millipedes and centipedes
A
- 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
28
Q
arthropods: crustaceans
A
- 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
29
Q
insects
A
- 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
30
Q
echinodermata
A
- phylum echinodermata includes organisms such as sea stars, sand dollars, and sea urchins
- all marine
- deuterosomes
- 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
