General characteristics of consumers
Depend on other organisms for food
Classified by what they eat: Herbivores (producers such as plants), Carnivores (animals), Omnivores (both plants and animals)
General characteristics of animals
- Eukaryotic with no cell wall
- Multicellular with cell specialization
- Heterotrophs
- Motile (at least one part of their lives)
- Respond quickly to stimuli
- Most reproduce sexually
9 main animal phyla
Porifera, Cnidaria, Platyhelminthes, Nematoda, Mollusca, Annelida, Arthropoda, Echinodermata, Chordates
11 groups of chordates
Lancelets, tunicates, hagfish, lampreys, jawed vertebrates, ray-finned fish, lobe-finned fish, amphibians, reptiles, birds, mammals
Adaptations needed for life on land
Amniotic egg, lungs, endoskeleton, internal fertilization
Lancelets
- most basal group
- only group that retains all chordate characteristics as adults
Tunicates
- sea squirts
- chordate characters apparent during larval stage
Hagfish
- most basal group of vertebrates
- skull made out of cartilage
- do not posses vertebral elements surrounding the dorsal nerve cord
- bottom dwelling scavengers
Lampreys
- rudimentary vertebrae (cartilaginous structures above notochord)
- jawless mouth
- cartilaginous skeleton
- rasping tongue penetrates fish skin and ingests blood
Jawed Vertebrates
- skeleton made of unmineralized cartilage
- dental elements were the first to be mineralized
- allowed animals to become scavengers and predators
ex: sharks, skates and rays
Ray-finned fish
- bony rays that support their fins
- ossified endoskeleton
- use gills to breathe and swim bladder to control buoyancy
- swim bladder is believed to be homologous to lungs
Lobe-finned fish
- lung is a modified swim bladder
- absorb oxygen and have gills
- bones in fins surrounded by a thick layer of muscle
- round fins and able to support weight
Amphibians
- have lungs (adults)
- gas exchange through the skin due to inefficient lungs
- must keep body moist
- developed skeletal structure to prevent collapse body collapse
- external fertilization (eggs must remain in water)
Reptiles
- lungs
- endoskeleton
- scales that create a waterproof barrier
- ectothermic (cold blooded, body temp regulated by environment)
- internal fertilization (sperm deposited directly within females)
- independent of water with amniotic egg
Birds
- lungs
- endoskeleton
- wings and feathers (to keep birds warm, endothermic, enable flight)
- internal fertilization
- amniotic egg
Mammals
- internal fertilization and internal development
- mammary glands (secretes milk)
- hair
- endothermic
- specialized teeth
- enlarged skull
Types of mammals
monotremes, marsupial, eutherians
Drawbacks of the amniotic egg
- insufficient protection from predators
- cannot survive drastic environmental changes
characteristics of the amniotic egg
- have amnion that protects embryo (in a fluid filled sac) from injury and dehydration
- Allantois: collects waste
- Yolk sac: nutrients (food)
- Chorion: gas exchange
monotremes
- small group of egg-laying mammals
- echidnas and the platypus
- lay eggs and mothers incubate eggs
echidna: after the egg hatches, young echidna sucks milk from pores in the mother’s skin
marsupials
opossums, kangaroos, koalas
- internal development of young but young are born prematurely and must be reared in pouches
- in the pouch: attach to a nipple and stay until they are able to forage for themselves
eutherians
- eutherians have a more complex placenta
- membranes found in the egg have been modified
- embryo is still surrounded by an amnion filled with amniotic fluid
- allantois and yolk sac becomes the umbilical cord. with part of the chorion, makes the placenta
- young eutherians complete their embryonic development within uterus, joined to mother by placenta
what is an amniote?
Land-living vertebrates which have an amnion around developing embryo.
Reptiles: amniotic egg, shell leathery/flexible
Birds: amniotic egg, bird shell inflexible (contains calcium carbonate)
Mammals: amnion, no shell
