Animal Diversity Flashcards
(20 cards)
What is an animal?
the unique aspect of animals is the way the cell is put together and how it interacts with other cells
Derived Traits:
1. Multicellular Ingestion heterotrophs
- Unique Tissues
- Lack cell walls
- Intercullular junctions
What is an animal?
multicellular Ingesting heterotrophs
multicellular Ingesting heterotrophs (compared to plants and fungi)
What is an animal?
unique tissues
e.g. muscle and nervous <- unique to animals BUT not all animals have muscles and nervous tissues
What is an animal?
Lack cell walls
Support provided by extracellular matrix (collagen(unique to animals) & proteoglycans) and cytoskeleton (microtubules and microfilaments)
What is an animal?
Intercellular junctions(
made of proteins
Tight junctions – (suture junctions) protein binding of neighboring plasma
membranes; water tight
Desmosomes – (anchoring junctions) – strong rivet like proteins that connect
tissues into strong sheets (e.g. muscles)
Gap junctions (communicating junctions) - provides a pore through which cellular products can be exchanged (important in heart beating) - heart communicates via gap junctions
Animals are _____.
Monophyletic
Evolutionary History of animals
- Choanoflagellates
- Late Proterozoic Eon(700MYA)
- Cambrian period(550MYA)
Evolutionary History of animals:
Choanoflagellates
closest protist relative of animals
Evidence
- Near identical morphology with sponge collar cells - Collar cells found only in animals and choanoflagellates (no other protist) - DNA sequence similarity
Evolutionary History of animals:
Late Proterozoic Eon
First animals 700MYA
- Ediacaran period – Ediacaran biota - first good animal fossils ca. 575 MYA
- Basic body plans developed (e.g. radial and bilateral symmetry; segmentation)
- segmentation is a crucial evolutionary step that allows animals to dominate
- segmentation = repeating units
- redundancy allows specific units to be mutated without destroying the organism. Allows significant diversification
Evolutionary History of animals:
Cambrian period
550 MYA
- Rapid increase in animal orders
- Major phyla established (see figure 32.11)
- Diversification likely caused by:
a. increase O2 – aerobic metabolism provides more ATP per unit of glucose
b. Diversifying selection – novel niche exploitation and predator prey dynamics
c. Hox gene duplications
- duplication = redundancy = evolution can toy with it - Animal diversity
- 75% of animals are insects
- 35% of all animals are beetles
- 5 % of animals are vertebrates
- < 0.001% are mammals(5000 or so total species but such a small amount of total animals)
Reproduction and Development
- Life Cycle
- Zygote Development
- Hox Genes
Reproduction and Development:
Life cycle
no alternation of generations
- Sexual reproduction (mostly)
- Flagellated sperm; large non-motile egg
- Diploid stage dominates the life cycle
- Fungi are the exact opposite of us
Reproduction and Development:
Zygote Development
- Zygote undergoes cleavage(cell divisions) –> Blastula (hollow ball)(blastocoel= hollow)
- Bastula undergoes gastrulation –> gastrula
- Gastrula has defined endoderm and ectoderm
Reproduction and Development:
Hox genes
master regulatory genes that dictateDEVELOPING body plan.
- Evolutionarily conserved – means strong selection against modification, causing
these gene to be similar across different animals. - Linear correlation btw body axis and chromosomal position (odd!)
- no explanation known
- Small mutations lead to big changes (e.g. antennapedia in fruit flies)
- legs where antenna should be
- Gene duplications allow greater anatomical complexity
Animal Body Plans:
Symmetry
Bilateral versus Radial
- Radial = cutting a circular pie = always symmetric
- Bilateral = 1 axis to cut on for symmetry
Animal Body Plans:
Tissues
Diploblastic (2 dermal layers – ectoderm and endoderm) versus triploblastic (3 layers – ectoderm, mesoderm, endoderm)
Evolution of true tissues (e.g. muscle, neural)
Animal Body Plans:
Body cavities
only triploblastic organisms – hold organs
Acoelomate - no body cavity
Pseudocoelomate - body cavity present; not completely lined with mesoderm
Coelomate - body cavity completely lined with mesoderm
Animal Body Plans:
Protostome vs. Deuterostome
Protostome - Mouth First
Deuterostome - Anus First
Animal Body Plans:
Protostome
Mouth First
Clevage
- Spiral – cells offset - Determinate – fate of early cells determined - Cells have a specific destiny of cell type
Coelom Formation
- Forms from mesoderm split
Fate of blastopore
- becomes mouth
Animal Body Plans:
Deuterostome
Anus First
Clevage
- Radial – cells linear - Indeterminate – fate of early cells undetermined - Cells still undertermined for what type of cell they will become
Coelom Formation
- Forms from archenteron out-pockets
Fate of blastopore
- becomes anus
