Arthropod I Flashcards
What is Arthropoda and what is it within?
Superphylum - Ecdysozoa
Phylum - Arthropoda
What does Ecdysozoa include?
Arthropoda
Onychophora
Tardigrada
What are the 5 subphyla (extinct and extanct) of Arthropoda
Extanct: Crustacean Hexapodes Chelicerata Myriapoda
Extinct:
Trilobite
Three characterisations of Arthropoda
Segmentation
Jointed appendages
Exoskeleton
Homonomous meaning
Example
Parts having a similar forms and structure and arranged in a series (eg. Fingers or toes)
Eg. Common ancestor of all Arthropoda had a series of similar segments
Heteronomous meaning
Example
Parts of an organisms differing in manner of growth, development or specialisation
Eg. Segments in extanct taxa differ as they are are fused/lost/specialised
Tagmosis
Grouping of segments with similar function/structure
Main three Arthropod tagmata
Head
Thorax
Abdomen
X
Trunk
Cephalothorax
X
X
Appendages on each segment
Article
Segments on appendages themselves
What do arthropod joints allow?
Appendage articles can be articulated despite the hard exoskeleton
What is at an arthropod joint?
Flexible cuticle allows bending
What controls arthropod appendage movement?
Antagonistic muscles
- flexor and extensor muscles allow movement of articles relative to each other
- protractor and retractor muscles allow appendage extension and retraction
What does the cuticle/exoskeleton provide?
Support
Maintains shape
Allows joint articulation
Provides protection against pathogens
What is arthropod cuticle made of?
Chitin (polysaccharide)
Sclerotisation
Biochemical process where protein chains that make up the cuticle are molecularly stabilised due to the establishment of cross chains
Sclerotin
Component of the cuticle formed by sclerotisation
Darker areas are more rigid
Ecdysis
Process of casting off old outer cuticle
Stages of moulting
Pre moult - detach old cuticle and develop new cuticle
Moult - shed old cuticle
Post moult - harden new cuticle
Intermoult - only roughly 10% of Arthropoda life
What is arthropod mortality linked to?
80-90% arthropod mortality is linked to moulting
Where is the poison claw?
On a centipede’s 1st trunk segment
Characteristics of myriapods
Head
Trunk
Single antennae
Open trachea
Diplosegments
Occur on millipedes which have two legs on each segment
Where are the modified anal legs of centipedes?
Last trunk segment
What are the 5 major subgroups of chelicerata?
Aranae (spiders) Scorpiones Acari (mites and ticks) Xiphosura (horse shoe crabs) Pycnogonida (sea spider)
What two body segments do chelicerates have?
+ two other characteristics
Cephalothorax
Abdomen
Chelicerae
Compound eyes
What type of lungs do arachnids have?
Book lungs
Silk use in spiders (4)
Feeding
Reproduction
Locomotion and dispersal
Sensing
