Arthropoda (lecture 12) Flashcards
Arthropods are segmented coelomates that have an exoskeleton and jointed appendages.
What type of animal did the arthropod evolve from?
Primitive annelids or ancestors common to both.
Metameric
The serial repetition of segments.
Tagmatisation
Different fused regions of the body for specialised functions.
Cephalothorax
Fused ‘head-thorax’
Why have arthropods been so successful?
The exoskeleton:
- Epicuticle (outer waxy layer): Water and gas proof
- Procuticle (cuticle underneath epicuticle)
Sclerotisation
The hardening of the procuticle
How do arthropods move?
Muscles called flexors and extensors operate antagonistically.
Ecdysis
The process of shedding the old exoskeleton.
Biramous
Two branched appendages
E.g: Trilobites
What is the trilobite subphylum?
Subphylum Trilobita
What are the subphylum and class of the King crab?
Subphylum Chelicerata
Class Merostomata
Prosoma
Large rounded dome: head and thorax
Opisthosoma
Hard and rough triangular abdomen
Phylogenetic tree?
Ecdysozoa=Nematoda and Arthropoda
