Lecture 5 - Phylogeny 2 Animal architecture Flashcards
Morphology based tree divide….
Bilaterians into 2 clades (deuterostomes & protostomes)
Assume developmental modes reflect phylogenetic pattern.
Recent molecular studies assign 2 taxa to deuterostomes…
Ecdysozoans : secrete external skeletons (exoskeletons) that are shed and replaced after they are outgrown (ecdysis)
Lophotrochozoans : Some phyla develop ciliated crown of tentacles to aid in feeding (lophophore) while others have distinct larvae stage (trochophore)
What are the 5 major levels of organization?
1) protoplasmic lvl
2) cellular lvl
3) Cell-tissue lvl
4) Tissue-organ lvl
5) organ - system lvl
Ecdysis
When exoskeleton are shed and replace after they are outgrown.
Animals are categorized in which developmental mode ?
protostome or deuterostome
Cellular lvl
multicellular organisms
cells show some division of labour
Protoplasmic lvl
-unicellular organization
- differentiated in subcellular structures,
organelles , cell as a whole
Cell-tissue lvl
cells grouped together & perform coordinated functions
Tissue-organ lvl
- tissues assembled into even larger functional units (organs)
- parenchyma (chief functional cells), stroma ( support tissues)
- embryo becomes layered during gastrulation
- Germ layer form various tissues & organs
Organ-system lvl
- different organs operate together as systems
- 11 different organ systems
- skeletal, muscular, integumentary, digestive, respiratory, circulatory, excretory, nervous,endocrine, immune, reproductive
Bilateral symmetry animals have how many germ layer?
3 germ layer
Triploblastic body plan
Radiata have how many germ layer ?
2 germ layer
Diploblastic body plan
Bilateral animals usually exhibits which type of cleavage ?
Spiral or radial
spiral cleaves ?
- planes of cell division diagonal to vertical axis
- smaller cells in large cell grooves
- early determination of each cell’s developmental fate (mosaic development)
Radial cleavages ?
-planes of cell division either parallel or
perpendicular to vertical axis
-tiers of cells aligned directly above one another
- each cell in early divisions retains capacity to develop into a complete embryo. (regulative development)
Why have a coelem ?
- protection
- skeletal substitute
- internal organ indépendance.
segmented body plan
-serial repetition of similar body segments
- along longitudinal axis (metamerism)
- segment = metamere/somite
- characterizes only 3 phyla (Annelida,
Arthropoda, Chordata)
allows segment specialization
What are the 4 tissue type ?
- Epithelial
- Connective
- Muscular
- Nervous
- epithelial
-covers internal/external
-protective covering on outside (e.g. skin)
also lines organs , ducts, passageways internally
- simple epithelia is found in all metazoan animals.
- stratified epithelia mostly restricted to vertebrates.
- Connective
-various binding & supportive functions
- relatively few cells but many extracellular
fibres & a ground substance ( MATRIX ) in
which fibres are embedded
- 2 basic types in vertebrates: loose & dense
also blood , lymph, interstitial fluid (lymph),
cartilage, bone
- Muscular
-most common tissue in most animals
-mostly originates from mesoderm
- comprised of muscle fibres
striated: skeletal & cardiac
smooth ( visceral)
- Nervous
- specialized for receiving stimuli & conducting impulses
- 2 basic types of cells
- neurons: basic functional unit
neuroglia: insulate & support
true tissues ?
Are collections of specialized cells isolated from other tissues by membranous layers. (not in sponges)
Ectoderm forms…
outer covering and central nervous system.
Endoderm form…
lines developing digestive tube & give rise to organs.
Mesoderm form…
Muscles & separate set of organs.
Cephalization
Central nervous system concentrated in head.
Development
- body plan develops as part of an inherited developmental sequence after fertilization & zygote formation
- single-celled zygote then divides (cleavage ) into smaller cells (blastomeres)
1 opening in gut is called
blind/incomplete gut
2 opening in gut is called
complete gut
creates a tube that allow food movement from mouth to anus.
Mesenteries
structures that suspend internal organs.
The gut is surrounded by …
A fluid filled cavity.
in 2 germ or 3 germ layer, which of the will the blastocoel persists ?
2 germ layers- blastocoel persists
3 germ layers - mesoderm can line the edge of the blastocoel.
