Lecture 21 Flashcards
What is ecdysis
molting
what is the cuticle
non-living outer layer of skin (gets shedded)
What is the cuticle made of
Chitin
can be either sclerotized (hard) or unsclerotized (flexible)
What is the epidermis
living cells that secrete substances to form the cuticle
What are the 3 layers of the cuticle
- Endocuticle
- Exocuticle
- Epicuticle
What are the steps of Moulting (Apolysis)
- Epidermis separates from endocuticle
- Secretion of moulting fluid
- Secretion of new cuticle
- Activation of enzymes in moulting fluid
- Shedding old cuticle
What are Nematoda
Roundworms, threadworms
-morphologically similar
-moult non-living cuticle
Characteristics of Nematoda
-have Alimentary Canal (complete digestive system)
-open circulatory system
-two sexes (hermaphrodites)
-are Eutelic
What does Eutelic mean
post-embryonic growth occurs by each cell growing, not by addition of cells
What are Phylum Arthropoda
-most species-rich phylum
-most successful & important group of animals
What is Tagmatization
Segmented body & jointed appendages arranged into functional units with specialized functions
What increases arthropod diversity
Tagmatization
Characteristics of Arthropods
-segmented
-cephalization
-open circulatory system
-respiration
-have sclerotized cuticle made of chitin that acts as an exoskeleton
What are Chelicerata
horseshoe crabs
-Ocelli (simple eyes)
-lack antennae
What is a Cephalothorax
fused head & thorax of spiders
