BIO2231 Lecture Notes - Lecture 9: Molecular Phylogenetics, Ecdysozoa, Arthropod Cuticle
Lecture 9 – Arthropoda I: Introduction
Phylum Arthropoda Introduction
• Metazoa → Eumetozoa → Bilateria → Protostomes → Ecdysozoa
• Ecdysozoa Characteristics
o Name: moulting and hormones
▪ In order to move through stages of growth, has to moult
o Hard cuticle made of organic material (three layered exoskeleton)
o No locomotory cilia
o No primary larva
o Internal fertilization with amoeboid sperm
o Primarily defined by molecular phylogeny
• Features
o Triploblastic, coelomate, protostome
o Bilaterally symmetrical
o Hard cuticle and moulting
o The animals with joined legs
▪ Arthron – join, pod – foot
o Biggest phylum
• Cuticle (exoskeleton)
o Functions:
▪ Protective but flexible
▪ Chemical barrier
▪ Muscle attachment
▪ Dessication prevention
o Strength – mix of chitin and cuticular
proteins
o Mix solidified in procuticle
o Chemical barrier - epicuticle
o Large metabolic investment
o Recycle
▪ Chitinases breakdown the chitin
find more resources at oneclass.com
find more resources at oneclass.com
