Animals I Flashcards
Animal traits
- multicellular
- chemoheterotrophic
- internal digestion
- capable of moving
- diplontic lifestyles
- over 1 mil
when and why were earliest multicellular animals possible
- Eucandian (600 mya)
- possible bc of oxygen
Choanoflagellates
- simple, flagellated, collared cells
- sis to animals
- sponges have choanoytes which are super similar
Gastrulation significance
- separates sponges (and placazoans) from rest of animals
- sponges don’t have true tissues and fdon’t do gastrulation
- eumetazoans go through gastrulation to form diploblastic or triploblastic organisms (2-3 embryonic layers)
General characteristics of animals vs synapomorphies
General: multicellularity, oogamy, chemoheterotrophic, internal digestion, movement
Synapomorphies:
- Uniques junctions b/t cells (gap, tight, desmosome) for structure and communication (not in all animals)
- Extracellular matrix compounds in common (collagen/proteoglycans)
Gastrulation definition
- process of development of an undifferentiaded blastula into embryo with 2-3 tissue layers
- involved invagination of blastula
Endoderm, ectoderm, mesoderm
Endoderm = innermost layer created during invagination –> gives rise to lining of digestive tract, respiratory tract, pancreas, and liver
Ectoderm = outer germ layer, formed from cells remaining on the outside of the embryo –> gives rise to nervous system, skin, hair, feathers, nails, sweat glands, oil glands, teeth
Mesoderm = middle layer made of cells that migrate between endoderm and ectoderm –> contributes to many organs including heart, blood vessels, muscles, and bones
HOX genes
- Encode for transcription factors that control ant to post dvlpmnt in embryo
- in all bilatarians
- there’s homologous genes in Cnidaria and Placazoa, but no true HOX genes in ctenophora or sponges
- duplication/diversification of these genes led to Cambrian explosion (maybe)
Protostome vs Deuterostome
Protostome:
- spiral, determinate cleavage
- schizocoeous
- mouth develops from blastopore
Deuterostome
- radial, indeterminate cleavage
- enterocoelous
- anus develops from blastopore
Who has segmentation?
- arthropods (prot)
- annelids (prot)
- chordates (deut)
Prob arose independantly in each
Pros of coelom
-isolates internal organs from body wall movements and makes animal more flexible
Coelom types
Acoelomates = no true body cavity (flatworms and nemerteas)
Pseuodocoelomates = animals with cavity, but not lined with mesoderm (rotifers and nematodes)
Coelomate = animals with true coelom that dvlps w/in mesoderm and forms a peritoneum
4 types of tissue
epithelial, connective, neural, muscular
Epithelial tissue
- sheets of cells that form boundaries with the environment or linings of body compartments
- good for selective permeability
- absorptive, protective, secretes stuff
connective tissue
- Dispersed cells in extracellular matrix
- collagen, elastin, fibrillin, CaPo3, plasma
muscle tissue
skeletal: regular actin and myosin filaments –> voluntary
cardiac: branching cells interwoven –> heart
smooth muscle: no regular actin/myosin arrangement –> involuntary movements
Neural tissue
- neurons and glial cells
- encode, process and store info from environment
- control physiology and behavior
- elec signals with axons
Porifera
- cells
- HOX
- What don’t they have
- where do they live?
- what types
- choanocytes
- no HOX
- no nervous system, true tissue, or symetry
- all aquatic
- Demosponges (90%) marine and freshwater
- Glass sponges–> silica skeletons (marine)
- Calcarea (CaCO3 skeletons) –> marine
Sponges
- sexuality
- larva
- internal skeletons
- mesoglea
- how old
- gonochoristic and hermaphroditic
- ciliated
- CaCO3 or silica
- jelly-like b/t epithelial layers –> produce spicules and amoeboid cells that digest filtered food
- fossils from 580mya, but chem evidence from 635 mya
Diploblastic aimals
- cnidaria, ctenophorans, placazoans
- have mesoglea
- simple nervous system with nerve nets in cten, cnid, and bilaterians (independantly)
- HOX like genes in cnid and plac
uncertain phylogeny
Ctenophora
- comb jellies
- marine worldwide
- basal group, but more complex structurally than sponges
- no hox genes
- complete gut
- 8 rows of cilia-bearing plates
- Feeding tentacles with sticky mucus to catch prey
- no nematocytes
Placazoans
-“flat animals”
-one of the earliest diverging diplblastic animals
-Hox-like genes
-small genome
-4 cell types
-no mouth gut, or nervous system
-adults = big flat things that stick to surfaces
-larvae are pelagic (traveling)
-
cnidaria
-precambrian to present
-sis to bilataria (together make eumetazoa)
-aquatic-mostly marine
-characterized by nematocytes
HOX-like homologs of bilatarian HOX
-nerve nets
-blind gastrovascular cavity
AMITOCHONDRIA
cnidaria types
Anthozoans: anenome and coral Scyphozoan = purple jelly Hydrozoan = hydra and obdelia cubozoan = box and moon jelly -10,000 species
Cnidarian feeding style
-predators that use toxin-containing nematocytsts (cnidocysts or cnidae) to capture prey
-nemtocysts = subcellular structures in specialized cells
(ove 30 types: penetrants, adhesives, lasso-like)
Cnidarian life cycle
- medusa and polyp phase
- dif groups are dominated by either phase
- coral and sea anemones are mainly sessile polyp-forming adults
- jellies are usually seen in the motile medusa phase
- obelia is sessile colonial polyp-forming adult with motile sexual phase
Hydra
- freshwater hydrozoan –> never exhibits a medusa stage
- small, predatory, usually sessile, but can move
- regenerative capacity–> doesn’t age
clownfish + sea anemone
- mutualism
- clown fish protects anemone and anemone doesn’t eat fish
- fish secretions help anemone not attack
- fish poop helps anemone
corals
- colonial polyps with hard exoskeletons (except Alcyonacea order)
- can capture prey with stinging cells, but many rely on photosynthetic dinoflagellates inside polyps
- colonies made of genetically identical polyps that reproduce asexually
- can also reproduce secually (most hermphroditic; some unisexual)
Coral bleaching
- b/c loss of endosymbiotic zooxanthellae, caused by stress
- continue to live, but growth is slowed
- increased levels of bleaching thought to be caused by pollution and global climate change
Cubozoans
- box jellyfish
- Chironex fleckeri produces super potent, fast-acting venom that causes pores to form in blood cells, releasing K –> heart contracts and stops quickly
