Lecture 17. A Flashcards
how many species have been identified until today and how many species are estimated to exist?
> 1 million species identified so far
Estimated 10-200 million species exist
Most are __?
invertebrates (97%)
Characteristics of ALL animals
Eukaryotic, no cell wall
Multicellular
Heterotrophic
all animals except __ have Nervous & muscle & tissue
sponges
kinds of symmetry in animals?
Asymmetrical
Radial (ex. phylum Cnidaria) Body can be cut into identical halves in more than 1 plane
BILATERAL only 1 cut along 1 plane results in 2 similar halves
which symmetry do most animals have
bilateral (only 1 cut along 1 plane results in 2 similar halves)
which of our organs regenerates tissues to some extent?
liver
animals Challenges to living on Land/ in water: Water loss
In water: Not a problem
On land: Can dry out (desiccation)
(waxy cuticle in invertebrates, tough skin in vertebrates)
animals Challenges to living on Land/ in water: Gas exchange
in water: Diffusion for simple animals, respiratory systems for others
On land: Reduced due to waxy cuticle. (lungs, tracheal tubes) NB wrt O2: more on land than in water
animals Challenges to living on Land/ in water: Structural support
In water: not a problem
On land: Gravity may cause collapsing (skeletal system)
animals Challenges to living on Land/ in water:Reproduction
in water: flagellated gametes swim to egg or internal fertilization
on land: Internal fertilization (except for amphibians)
animals on land characteristics
Land
potential for drying out (desiccation), temperature change
Need support against gravity
Most animals live on land
animals in ocean characteristics
In the ocean
Relatively stable temperatures, food, fluid
Disadvantages: Currents
animals in fresh water characteristics
Fresh water
Less constant environment, osmoregulation (get rid of excess water) required
how many major animal phyla
9
which phyla of animals have no blood (no circulatory system)?
the first 4
- porifera : sponges
- cnidaria : jelly fish
- flat worms
- round worms
which phyla of animals have a backbone?
chordate
animal phylum and an example of each?
- porifera : sponges
- cnidaria : jelly fish
- flat worms
- round worms
- molluscs: snails
- segmented worms: earth worms
- arthropods: spiders
- echinoderms: starfish
- chordates: birds
75% of animals are in the phylum __?
Arthropoda (Exoskeletons invertebrates)
how long did the Cambrian explosion last?
10 million years
what is the cambrian explosion
Cambrian explosion: abrupt appearance of major animal groups
only 2 phyla present before the Cambrian explosion (fyi porifera ie sponges & Cnidaria ex jellyfish) ie only water-dwelling animals
Almost all living animal phyla appeared within a few millions of years.
Appearance of animals?
LAND PLANTS, THEN LAND ANIMALS. BCUZ ANIMALS EAT PLANTS
Physiological systems: 3 Skeletons
Exoskeleton: external, surface
Endoskeleton: internal (in vertebrates)
Hydrostatic skeletons: fluid under pressure in a closed body compartment
Exoskeleton and its function?
external, surface (since this is the type of skeleton in invertebrates, it is the most common type of skeleton)
Support, protection
Endoskeleton and its function?
internal (in vertebrates)
Support, protection of internal organs, movement, store minerals
Hydrostatic skeletons and their function?
fluid under pressure in a closed body compartment
movement
External Fertilization in vertebrates?
Most fish (cold-blooded) - Sharks have internal fertilization
Amphibians (cold-blooded)
frogs
Internal Fertilization
Reptiles (cold-blooded)
Birds (warm-blooded)
Mammals (warm-blooded)
Amniotes?
vertebrates which have a fetal tissue known as the amnion, which surrounds and protects the fetus
Reptiles, birds, mammals
Amniotic cavity with fluid function
protects from injury & dehydration (no desiccation of developing offspring)
Yolk sac: nutrients
(like the seed)
How do the embryos breathe inside the amniotic eggs?
through the pores
5 Criteria of classification of animals?
Tissue organization: present or absent
Body symmetry & development
Body cavity *
Embryonic development
Segmentation
if an organism has no true tissues, it belongs to which phyla?
No true tissues: Phylum Porifera (sponges)
90% of chordates are __
vertebrates
Placenta? its function?
Organ of exchange (food, wastes) between mom & developing embryo
Allows young to stay in mom until embryonic development complete or almost complete
oviparity?
expulsion of undeveloped eggs rather than live young
viviparity?
Placental mammals
The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of
true tissues
