Bio final chapter 23,24,25 Flashcards
Shared derived features of ecdysozoans
Cuticle
Cuticle
tough outer layer outside of epidermis for protection and formation
3 layers
procuticle chitin
-endocuticle
-exocuticle
epicuticle- thin waxy water resistant layer no chitin
Sclerotisation
happens to cuticle to make it hard and rigid
cross linking of polymers and proteins
What is Ecdysis
ecdyzoans shed entire cuticle
ecdysis helps them grow in increments
tissue cam be regenerated
8 steps of ecdysis
- apolysis- ecdyzoans become inactive and cuticle seperates from epidermis
- inactive enzyme of moulting fluid is secreted into space between cuticle and epidermis
cells are enlarged and surface area increased - proto epicuticle is deposited on surface
- Moulting fluid is activated old cuticle is digested by epidermis to build new cutcle scleroted cuticle is not digested
- Moulting fluid is reabsorbed
- deposition of new cuticle
- old exocuticle/ epicuticle is moulted
- swallow air to expand cutcile
-initially wrinkled
-new cuticle expands
- swallow air to expand cutcile
- outer layer of new procuticle is sclerotised by secretions via cuticle ducts
Arthropod characteristics
1.segmented body- embryos are segmented arranged into functional units called tagmata.
2. Jointed paired appendages
3.sclerotised cuticle chitin
4. prominent cephalisation- head is formed by fusion of several segments complex organs
5. reduced coelom- primary cavity is haemocoel
6.open circulatory system fluid called haemolymph
Tagmatisation
fusion of body segments
3 lineages of arthropods
subphylum- chelicerata
subphylum- myriapoda
clade- pancrustaceans
Chelicerata
spiders scorpions mites
1.two main tagmata- dorsal skeleton anterior cephalothorax, six pairs of appendages no anntenae
uniramous appendages
-posterior abdomen- no appendages digestive and repro organs
2. chelicerae as mouthparts
modified appendages positioned in front of mouth homologous to antannae fangs or pinchers
Myriapoda
millipedes and centipedes
body plan less tagmentised then chelicerates
eyes, three pairs of mouth parts and one antennae
jointed uniramous legs
respiratory via tracheal system-in spiracles circulates body via tracheoles and haemolymph
direct development without larvae stage
Pancrustacea clade
paraphyletic custacea and hexapoda
Pancrustacea- crustacea
Body plan
1.three tagmata -head thorax and abdomen
head and thorax can merge into cephalothorax
2. covered by carapace
3. compound eyes
4. biramous appendages for specialized functions
-two antennae
-two pairs of maxillae
-paired segments of mandibules
-thoracic and abdominal limbs for locomotion
5. exoskeleton stengthened by biomineralisation
6, O2 is transported by respiratory protein haemolymph
Pancrustacea- hexapoda
insects
feeding on gymnosperm and pollinating angiosperm
small groups of wingless hexapoda
1. consistant tagmatisation
-head antennae three pairs of mouth parts
-thorax with three pairs of jointed uniramous legs and maybe wings
-abdomenon lacking paired appendages
2.gas exchange via tracheal system
-spiracles on lateral aspects of tagmata, branched cuticle lined tubes distribute oxygen to tissues
most hexapods lack o2 carrier
Insect wings
apterygota-insects that lack wings
pterygota- wings is a synapomorphy
wing only evolved once in this clade
two pairs of wings on thorax
wings are extensions of cuticle with various degrees of sclerotisation
Clade deuterostomia three phyla
Hemichordata
echinodermata
chordata
Deuterostomia characteristics
bilateral symmetry at least once postnatal development
triploblastic
coloem formed by enterocoely
blastopore develops into anus
Echinodermata
sea stars brittle stars and sea urchins sea lilies and sea cucumbers
slow moving sessile
Characteristics
1.adults radial symmetry penta think star mouth centre anus back bilateral evolve first radial evolved second
2.endoskeleton with ossicles- ossicles are calcerous plates positioned within dermal tissue
3. unique water vascular system
4. diffuse nervous system without a centralised brain
5. usually have individuals with separate sexes sperm eggs released into water for external fertilization
no parental care
Echinodermata water vascular system
derived from coelom
connected to sea water through madreporite
Madroporite, ring canal in central disk hydaulic canals ampullae and podia
Hydraulic canals lead to hundreds of fluid filled tube feet
what are tube feet
adapted for locomotion, respiration, mucous production and sensory perception
composed of
ampullae, podia, suction disks and muscular tissue
controlled by water pressure on ampullae and podia
attached to substrate by suction
Echinodermata phylogeny
asteroida, echinoidea, holothuroidea
Asteroidea
echinodermata
star
feed on molluscs pry shell open with tube feet evert stomach to digest
asexual and sexual
five or more arms around central disk
echinoidea
echinodermata
sea urchin and sand dollars
herbivores
asexual and sexual
asexual rare only present during larvae stage
no arm
5 rows of tube feet
slow movement by tube feet or spines
