Animal Characteristics (7) (EHMW
- Eukaryotic
- heterotrophic
- multicellular
- no cell wall
- diplontic
- somatic cells are diploid
- motile at some point
- many, not all have internal digestion (continuous tube)
Eukaryotic
membrane bound organelles
true nucleus
Heterotrophic
- different feeding
- use pre-formed organic materials as E and C course
- modes of feeding: herbivores, carnivores, filter feeders, parasites, detritivores, omnivores
Multicellular (3 benefits)
- cells are specialized
- organisms can grow in size
- one large cell, low surface area to volume ratio, multicellularity helps overcome this constraint on growth
No cell wall
- hydrostatic skeleton
- exoskeleton
- endoskeleton
Hydrostatic skeleton
- muscles contract against fluid-filled cavity
- ex. worms
exoskeleton
- external
- non living covering that does not grow with animal
- ecdysozoans
ecdysozoans
moulting animal
endoskeleton
- internal support
- vertebrates
- some inverterbrates (CaCO3)
Motile at some life stage (benefits of that? (2))
- reduce competition
- enhance genetic diversity
somatic (body cells) are diploid
- undergoes meiosis to produce haploid cells
- fuse to form zygote
diplontic
fungi, haplontic
plant, alternating
animals, diplontic
most animal has tissues
tissues = groups of similar cells organized into a functional group function as organs to complete complex tasks
Origin of Animal (When? Closest living?)
First animal: 1.2 BYA - 700 MYA, marine
closest living relative to animal are colonial choanoflagellate protists
Animal Diversification (What happened?)
- “Cambrian explosion”
- 542 - 488 MYA
- rapid diversification
- many fossils found in Burgess Shale, BC
animals are monophyletic (one common ancestor) Evidence?
similar gene sequences
similar extracellular matrix molecules
unique types of junctions between cells
Tight Junction
- abundant in epithelial cells
- bound tightly together
- cell-cell attachment structure that links the plasma membranes of adjacent animal cells
- forms a barrier to restrict movement of substances in the space between the cells
Desmosomes
- connection btwn cytoskeletons
- attaches cytoskeleton of adjacent animal cells together
Gap Junctions
- connect cells to cells
- directly connects the cytoskeleton of adjacent cells
- allows the passage of water, ions, and small molecules between the cells
- found in muscle and nerve tissues
- allows rapid communication between cells
Sponges (Porifera) (pore bearing)
- 9000 (mostly marine)
- sessile as adults, motile as larvae
- spicules and a network of elastic fiber for support
- morphology is variable
Filter Feeding
Choanocyte is similar to choanoflagellate
water goes through the pores and is pumped out from the osculum
cells are embedded in a jelly matrix
There is no true tissue (other than epithelial) or organs
Support structures - Sponges
extracellular matrix
spicules
spongin
extracellular matrix - Sponges (3)
- non cellular
- support
- collagen, glycoproteins
spicules
- made of CaCO3, SiO2
- provides rigidity
