Invertebrate Animals Flashcards
Animal 7 characteristics
Eukaryotic
Heterotrophic
Multicellularity
No cell wall
Motile at some life stage
Somatic cells are diploid
Diplontic life cycle
Eukaryotic
True nucleus
Membrane-bound organelles
Compartmentalized cytoplasm
Heterotrophic
Use pre-formed organic materials as energy and carbon source
Predators
Herbivores
Filter feeders
Parasites
Detritivores
Omnivore
Animals have specific digest organs
Multicellularity
Important evolution innovation, only once in animals
Advantages:
1.Cells become specialized to carry out specific functions
2. Longer lifespan
3. Organisms can grow in size
Large-cell problem
Low surface area, surface area-to-volume ratio
Large cell hard to exchange nutrients
Larger, exchange capacity decrease
Multicellularity overcomes the constraint on growth resulting in requirements for development
Tissue
Tissues: groups of similar cells organized into a functional unit
4 basic types:
Muscle-active contrastive tissue
Nervous-comprises the central nervous system or the peripheral nervous system and irregulars and controls many body activities
Connective-made up of cells that are separate by non living materials which is called an extracellular matrix
Epithelial- cells cover the organ surfaces
Organs
Tissue function together as organs to complete complex tasks
Eg. digestion, absorption
villi
No cell wall, what support structure?
Hydrostatic skeleton
Exoskeleton
Endoskeleton
Hydrostatic skeleton
Found in soft bodied organisms
1.Muscles contract against fluid-filled cavity
2.simple but efficient movements
3.limited possibility for the attachment of limbs
4.dependence of a humid environment
Muscle fiber: longitudinal muscles and circular muscles
Exoskeleton
1.Firm, rigid structure
2.Non-living covering
3.Does not grow with animal
4.Molting-ecdysozoans
Endoskeleton
1.rigid structure inside body
2.internal support
3.vertebrate-living tissue
4.some invertebrates-non living tissue (spicules in sponges and cuttlebone in cuttlefish)
Motile at some life stage
- Movement reduces competition
- Enhances genetic diversity
- Expends the distribution of range
Eg. Barnacle larva
Somatic cells are diploid
Germ cells N
Fertilization
Zygote 2N
Mitosis
Body cells 2N
Meiosis
Germ cells
Exceptions: the male of the honeybee is haploid
Animals are diplontic
Diploid dominant life cycle
Evolution of Animals
About 35 phyla
10 million estimate
1.4 million classified
97% invertebrate
Moniphyletic
Time animals evolve: Late Precambrian
First animal: 700 MYA
The Cambrian Explosion
542-488 MYA
The most explosive wave of diversification
Chengjiang
Burgess Shale, BC
Animals are monophyletic
- Similar gene sequences (hox genes: the organization in of the hox genes in the chromosome is the same as the order of their expression)
- Similar extracellular matrix molecules (collagen fibers, proteoglycan complex)
- Unique type of junctions among cells (tight junction, desmosome, gap junction)
Tight junction
Seal cells together and are found in the epithelial tissue
Special protein in cell membrane form a water tight seal
Common in epithelial tissue
Desmosomes
Connect the cytoskeleton of cells
Abundant in epithelial tissue
Gap junction
Act as channels between cells
Found in muscle and nerve tissues(where rapid communication is important）
Embryonic development: zygote to multicellular organism
1.Fertilization: single sperm combining with a single egg cell
2.Zygote: first cell of next generation, diploid cell resulting form union of 2 haploid gametes, combined from zygote
3.Embryo: young animal, contain within a protective structure(egg shell or uterus)
Process during embryonic development
- Cleavage: multiple rounds of rapid cell divisions(mitotic), but the overall size of the embryo is not changing(because the cytoplasm is not replenishing during this time). Finally become a morula
Create Blastomere 卵裂球
During this stage, cleavage cytoplasm it determinants found in specific location in the egg cytoplasm, these determinants will determine the fate of the cells. 基因调控分化
- Gastrulation: infolding , invagination to create the embryonic tissue layers (2 or 3 tissue layers). During this stage, the body need a well defined head, tail axis
blastocoel囊胚腔——blastula 囊胚——early gastrula - Cellular differentiation: immature cell take on individual characteristics and reach their mature form and function
major feature of the gastrula
- Blastocoel: 细胞里的腔
- Archenteron: digestive space
- Blastopore(mouth and deuterostomes肛门)
Germ layers:
1.Ectoderm: outer skin, developed to epidermis, nervous system
2.Endoderm: inner skin, developed to digestive and respiratory tracts
3. Mesoderm: another layer on the top of the endoderm, developed to muscles, skeletal system and part of gonads(most internal organs)
Organism with 2 germ layers are diploblastic(2 buds), 3 germ layers are triploblastic
Body symmetry
- Asymmetry: no axis divides body into equal halves
Eg. sponges - Radial symmetry
Eg. Jellyfish - Bilateral symmetry: midsagittal plane(between eyes)
dorsal, ventral, anterior, posterior
Eg. Most animals
Some animals will shift to another body symmetry when they grow up (sea star: larva bilateral symmetry, adult radial symmetry)
Sponges (Phylum Porifera)
Earliest animals, fossil record (700 MYA)
Sessile as adults, motile as larvae (dispersal)
-Primitive features (specialized cells but no true tissues or organs)
-Endoskeleton: spicules and a network of elastic fibres for support
~9,000 species, mostly marine
Inhabit a wide range of habitats
Anatomy of a sponge for Filter Feeding
Digestion: intracellular
Respiration and excretion排泄: diffusion
-Choanocyte: collar cells, have flagella (similar structure with the choanoflagellate protist)
-Osculum: water blow out via osculum, locate at the top of central cavity
Anatomy of a Sponge
3 layers:
1.outer layer: epidermal cell, flat cells
2.middle layer: gelatinous mesohyl (jelly matrix), with amoebocyte cell embedded in
Also have endoskeleton made up by spicule and spongin and fibers.
3.inner layer: choanocyte with their endoflagella
Support structure in the middle layer
1.Extracellular matrix: non-cellular, collagen and glycoproteins ,some support
2.Spicules: CaCO3, SiO2, provide rigidity (some have SiO2-rigid structure)
3.Spongin: protein fibers and flexible support
Asexual reproduction of Sponges
1.Fragmentation:
external budding, not self-induced, brought about by waves or predators(crack, and part of it continue to grow)
2.Internal budding:
Gemmules 芽球: clone of parent, happen in internal buds
Enclosed by a protective covering
Sexual reproduction of Sponges
-Hermaphroditic: most species, can produce both eggs and sperms, but only produce one at one particular time, so cannot self-fertilize
-Broadcast sperm: release all the sperm all at ones
-Choanocytes: trapped the sperm
-Mesohyl: eggs store, fertilize, and develop in the matrix
-larve released back to water, can swim using cilia, later settle on suitable substrate基底
Cnidaria, Cnidarians
Diploblastic
Radially symmetrical
Simple nervous and muscular tissue
~11000 species most marine, diverse in body size
jellyfish, sea anemones, corals, hydrozoans
Generalized body plan of a cnidarian——Diploblastic
Mouth/anus: from blastopore, top of the cavity
Gastrovascular cavity: from archenteron, bottom of the cavity
Gastrodermis: inner layer, from endoderm
Epidermis: outer layer from ectoderm
Mesoglea: inner part between gastrodermis and epidermis, collagen and proteoglucans
Cnidarian Body Orientation
1.polyp: mouth open upward
eg. sea anemone
2.medusa: mouth open downward
free to move eg.jellyfish
Most life cycles include both body plans: polyp is usually in the asexual stage, medusa is usually in the sexual stage (corals is one of the exceptions)
How do cnidarians obtain energy?
Carnivorous: inject toxins and capture prey
-Cnidocyte: usually located near mouth or in tentacles
-Nematocyst: with barbs and contains toxins
Extracellular digestion in gastrovascular cavity
Corals and anemones can obtain a large proportion of their energy from symbiotic algae (through photothesis)
Cnidarians: diversity
1.hydrozoa
2.scyphozoa
3.cubozoa
4.anthozoa
Hydrozoa
freshwater
no medusa stage
moves by gliding, somersaulting or floating
Have a Bubble for floating and sinking, mouth, basal disk
-Hydra: simple nerve net (No integration of signal), radial symmetry so sensory info can com in from any direction
-Life cycle of the hydrozoan Obelia
-Portuguese man-of-war: colonial polyps specialized for different functions; gas-filled float: pneumatophore; tentacles contain cnidocytes
Scyphozoa (true jellyfish)
Large\thick mesoglea
Bell shape-all the sensory cells clustered at the edge of the bell
Some has strong nematocysts(刺细胞)
Prey on fish larvae and zooplankton, important food for leatherback turtles
Eg. Cassiopeia
Upside down jelly
Symbiotic algae in the tentacles(触手)
Get O2 and nutrients from symbionts
Lives in mangrove swamps(红树林沼泽)
Cubozoa (box jellyfish)
Cube shaped Medusa
Very painful stink, and some times deadly for human
Anthozoa (flower animals)
~6000 species
-Sea anemones:
Retract tentacles in defense, have cnidocytes
Mutualistic relationships (+/+) with particular species of fish and shrimp
-Corals:
Form colonies of a lot of genetically identical polyps, polyps secrete calcium carbonate for the hard skeleton, creating framework of the coral reef
Coral also have mutualistic relationships with dinoflagellates(need clean water), coral protect them and they can do photosynthesis, produce nutrients and O2, help coral remove waste
Coral bleaching: caused by many factors , water temp, UV, pollution, disease
