lecture 20: animals Flashcards
Ecological roles?
- Consumers
- Predators/Prey
- Parasites/Hosts
- Mutualists
NOT primary producers, because there are no photosynthetic animals
Roles in human disease (2)
- Reservoirs (habitat of pathogens)
2. Vectors for pathogens (transport pathogens)
Morphology?
Multicellular: many have specialized tissues (organs) ,some type of skeleton, some are microscopic (still multicellular)
Mode of nutrition
All are chemoheterotrophs, MOST ingest food
Reproduction and development?
Sexual and/or asexual reproduction, Metomorphosis and ecdysis (molting)
Motility
Move under own power at some point in life cycle; Most = motile as adults
Structural features
Eukaryotic cells with no cell walls, bu extensive extracellular matrix (ECM) —> cells connected indirectly, many have muscle and nervous tissue —> communication between tissues
What is unique to animals?
- Metamorphism
- Ecdysis (molting)
- No cell wall
- ECM
- Muscle and nervous tissue
History of animals (2)
- Cambrian explosion: rapid appearance of most in animal phyla (first animals were aquatic) 542 MYA
- Tetrapods evolved from a lobe-fin fish-like ancestor to colonize land 390 MYA
Choanoflagellate cells vs Sponge cells
Choanoflagellate = sessile protists, some are colonial
Sponge = multicellular sessile animals (attached to something)
—> Both have similar structure
Why are animals chemoheterotrophs?
Obtain organic nutrients from other organisms via:
- Ingestion and digestion
- Absorption (endoparasites)
How do animals ingest food?
- Suspension feeders: aquatic, filter materials in water
- Deposit feeders: digging in soil
- Fluid feeders: plants, mutualism with ants
- Mass feeders: consume other animals
Description of animals’ organ systems
- Respiratory system, Circulatory system, Digestive system, Excretory system, etc —> different types of each systems exist in animals
- Digestive system: to digest food that they ingest
- Need systems to efficiently exchange materials within the body and with environment
- Exchange systems + circulatory system —> transport nutrients, wastes & respiratory gases to different part of body
How are why (3) animals move/use locomotion?
Move with their own power at some point during their lifetime 3 functions: 1. Finding food 2. Finding mates 3. Escaping predators
Movement with simple structures (cilia, flagella), but also complex limbs with muscles attached to hard skeleton
Why do animals use skeletons? 4 types?
Support, protection and movement
- Spicules in sponges
- Exoskeletons
- Endoskeleton
- Hydroskeleton (made of water)
How do animals reproduce?
Diverse ways to reproduce
- Only asexually (Rare)
- Only sexually (humans)
- Both ways depending on environment
- Hermaphrodites (sexual reproduction while having both male and female sexual organs)
Methods of asexual reproduction in animals? (3)
- Fragmentation and regeneration: animal body fragments and each piece becomes a clone of parent OR piece of parent is detached and it grows and develops into a clone
—> Study of stem cells and to regenerate our tissues (for medicine) - Fission and budding: new clones grow out from parent organism —> elongates and separates from parent
- Parthnogenesis: development of unfertilized egg into offspring in females (not always clones)
Types of fertilization during sexual reproduction?
- Internal: via copulatory organ —> important adaptation to reproduction in land —> to protect male gametes and prevents its desiccation
- External —> ex: sperm released in water
Two types of development after sexual reproduction
- Oviparous: species lay eggs outside to develop independently of mother —> vast majority of animals
- Viviparous: species retain embryos in female’s body during development —> live birth
Metamorphosis? 2 types?
Change from immature body type to adult body type
- Hemimetabolous (incomplete): immature body = smaller versions of adults, eat same food
- Holometabolous (complete): larvae stage —> different from adults, eat different food, then become adults
Ecdysis?
Shed stiff cuticle (Exoskeleton) as they grow and produce anew one to fit the bigger body
- Arthropods and nematodes (round worms) develop with ecdysis
“molting” = shedding of exoskeleton
Description of sexual reproduction in water (2)
Aquatic species: don’t have to worry about drying out of gametes
- Aquatic species lay unfertilized egg cells in water (eggs and sperm released in water)
- External fertilization (can do internal too, but more for land)
Description sexual reproduction on land (3)
- Internal fertilization:
- Direct transfer of sperm during copulation
- Indirect transfer of sperm via spermatophore (sperm packet) produced by male and transferred into female - Ovipary via amniotic eggs: reptiles, birds, egg-laying mammals lay amniotic eggs on land’
- Vivipary: viviparous mammals retain embryo within body during development —> live birth
What is an amniotic egg? (7) Functions? (2)
- Watertight shell enclosing:
1. Water supply: Albumen (also provides mechanical support)
2. Food supply: Yolk sac
3. Gas exchange surface: Chorion
4. Waster repository for embryo: Allantois
5. Amnion that contains embryo
6. Amniotic fluid
7. Extra embryonic membranes: create compartments with different functions - Nourishes developing embryo with organic compounds and water
- Protects embryo from: desiccation, mechanical shock, accumulation of harmful waste products
