Chapter 25 & 26 Notes
Characteristics of Animals
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Multicellular Eukaryotic Organism
Feed on other organism
Have ways of moving that enable them to obtain food
Cells do not have cell walls
Are heterotrophic not autotrophic
Can move from place to place to obtain food
Other animals, barnacle remain stationary and draw food to it
Some are vertebrates- they have a backbone
Some are invertebrates- no backbone- starfish insects etc.
Some (sponges and coral) move only during the early stages of their lives- they hatch from egs
into free swimming larvae- They become attached to a rock (etc.) when they become adults
11. Organisms that don’t move from place to place are known as sessile organisms
Animals must digest food
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Animals break down or digest their food once they have consumed it
Some animal digestion takes place in an internal cavity
In other animal’s digestion is carried out within individual cells
Most food is stored as fat or glycogen and used as energy when food is not available
Only one opening to the flatworms digestive tract
The earthworm has 2 openings to its digestive tract- one at each end
Animal cell adaptation
1. Most animal cells are adapted for different functions
A. Nerve cells- conduct information
B. Red blood cells- transport oxygen
C. Muscle cells- make movement possible
D. Stomach lining cells- secrete digestive enzymes
Development of animals
1. Zygote- a single fertilized egg
2. Division of the egg
A. Cleavage- division of the zygote
B. Blastula- a single layer of cells surrounding a fluid filled space
C. Gastrula- a structure that is made up of 2 cell layers
1. The outside layers of the gastrula is called the ectoderm
2. The inside layer is the endoderm
3. Ectoderm- develop into skin and nervous tissue
4. Endoderm develop into the lining of the digestive tract
5. A protostome is an animal with a mouth that develops from the opening in the gastrula earthworm
and insects
6. A deuterostome is an animal in which the anus develop from the opening in the grastula
Mesoderm
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Is a third cell layer former in the developing embryo
Meso means middle
Develops from the clumps of cells that break off the endoderm
Mesoderm gives rise to muscles circulatory organs and reproductive organs
Some cells begin secreting calcium- forms spines in the adult sea urchin
What is symmetry?
1. Symmetry refers to balance in proportions of an object or organism
2. All animals have some kind of symmetry
3. An animal that is irregular in shape has a body plan that exhibits asymmetry- usually sessilesponges
4. Radical symmetry- hydra
5. Animals with radical symmetry can be divided along any plane through a central axis into
roughly equal halves
Lateral Symmetry
1. An organism with lateral symmetry can be divided down its length into similar right and left
halves hat mirror images of one another
2. In such animals the antenor or head end has a different appearance than the postenior or tail
end
3. The dorsal or back surface also looks different from the ventral or belly surface
Bilateral Symmetry and Body Plans
1. Animals that are bilaterally symmetrical also share other characteristics
A. Have body cavities in which internal organs are found
B. Acoelomate- flat worms have 3 cell layers with a digestive tract- but no body cavities
C. Pseudocoelomates- roundworms
D. A spuedocoelem is a fluid filled cavity partly lined with modern mesoderm
E. Roundworms have mouth-takes in food; middle region-digests; anus- expels waste
Coelom provides space for internal organs
1. Earthworms have a more complex body plan than ringworm
2. A coelom is a body cavity completely surrounded by mesoderm
3. Humans, insects, fish, etc. have a coelomata body plan
4. In coelomata the digestive tract and other internal organs are attracted by double layers of
mesoderm and are suspended within the fluid filled coelom
Animal protection and support
1. An exoskeleton is a hard waxy covering on the outside of the body that provides a frame work
for support, which prevent water loss and provides protection
2. Exoskeletons are common in invertebrates
A. An invertebrate is an animal that does not have a backbone- crabs, spiders, grasshoppers
etc.
3. An eudoskeleton is a support framework housed within the body
A. A vertebrate is an animal with a backbone
B. Provides protection for internal organs and provide an internal brace for muscles to pull
against
Sponges, cnidarians, flatworms and roundworms
What is a sponge?
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A sponge is asymmetrical
Come in a variety of colors, shapes, and sizes
As small as a quarter some are as large as a door
Are classified in the invertebrate phylum, porifera- pore bearing
Most live in the ocean
Are sessile
They get their food by filter feeding
A. Food is filtered from water as it passes by or through
8. Sponges have no tissues organs or organ system
9. They have 4 types of cells that perform all necessary functions
A. Pore cells- for food getting- bring water carrying food
B. Epithelial cells- respond to touch, chemical etc
C. Collar cells have flagellum which beat and draw water in
D. Amoebocyte- carry nutrients aid in reproduction and they make spicules
10. Form one cell to cell organization
A. They can separate and then come back together again
Reproduction in sponges
1. They reproduce both sexually and asexually
2. Asexually- fragments break off or they grow and bud
A. Sometimes buds remain attached and develops into a colony
3. Sponges are hermaphrodites- sperm and egg are both produced
4. Sperm is exchanged
5. Fertilization may be external or internal
6. Most reproduce sexually through internal fertile results in free swimming larva
7. Sponges can regenerate lost parts
What is a cnidarians?
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Cnidarians are a group of marine invertebrates
9000 species of jellyfish, coral, sea anemones and hydra
Have radial symmetry
Only have one body opening
Are 2 cell layers thick
Have a simple nervous system- cell that contract like muscles
They display two basic body forms at different stages of their life cycle
A. Polp stage- a tube shaped body with a shaped body with a mouth surrounded by
tentacles
B. Medusa- a body form shaped like an umbrella with tentacles hanging down
Digestion in cnidarians
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They capture or poison their prey with nematocysts
A nematocysts is a capsule that contains a coiled or threadlike tube
The tube may be sticky or barbed
Have a gastro vascular cavity in which digestion takes place
Oxygen enters cells directly
1. Oxygen diffuses directly into the body cells from water and CO2 and other waste diffuses out of
the cells directly into the surrounding water
Nervous regulation in cnidarians
1. They do not have a nervous system
2. They have a nerve net that conducts impulses from all parts of the body- no brain
Reproduction
1. Both sexually and asexually
2. Polps- budding- asexual
3. Medusa- sexual- sperm and egg
Other cnidarians
1. Hydrozoans- Portuguese man of war
2. Scyphozoans- jellyfish painful sting
3. Anthozoans- corals- build coral reefs- ocean forests
Flatworms
1. He least complex of worms belong to the phylum platy helminthes
2. Are acoelomates with thin solid bodies
3. The most well-known members of this phylum are:
A. Class cestota- parasitic tapeworm
B. Class trematoda- flukes cause disease in humans
C. Class turbellaria- free living planarians cause no disease
Feeding and digestion in planarian
1. They have a pharynx and mouth that sucks in food and digests it in a gastro vascular cavity
Nervous control in planarians
1. Eyespots- sensitive to light
2. Ganglion- is a brain- like structure
3. 2 nerve cords that run the length of their body
Reproduction in planarians
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Most are hermaphrodites
They can exchange sperm
They fertilize internally
Can also reproduce asexually by fission
They can also regenerate lost parts- the head will grow a new tail and the tail will grow a new
head
Parasitic flatworms
1. Adapted to obtaining their nutrients from inside the bodies of one or two kinds of hosts
2. They have mouth parts with hooks that serve to hold the worms position inside the host
3. There is loss demand for a complex nervous or muscular system
Tapeworms adaptations
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Are parasitic flatworms of the class cestoda
They live in the intestines of dogs, cats, cattle, monkeys, and Jordan Samuelson
Poor sanitation
Can grow to be 10 meters in length
Their head is called scolex. Their body sections are called proslotted
Each proslotted may contain 100,000 eggs
Life cycle of flukes
1. A parasitic flatworm human and snails
Roundworms
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They belong to the phylum nematode
Live in soil, animals, and plant, etc.
Most are free-living, many are parasitic
Are smaller than flatworms
Some round worms
A. Arcaris- hookworms
B. Pinworms
C. Trichinella- uncooked pork
6. Parasitic roundworms
A. Have a thick outer covering that protects them from being digested by the host