Ctenophora

• Phylum Ctenophora Greek kteno, comb + phoros, to bear’
• Diploblastic or possibly triploblastic, tissue-level organization
• Biradial symmetry
• Gelatinous, cellular mesoglea between the epidermal and gastrodermal tissue layers
• True muscle cells develop within the mesoglea
• Gastrovascular system, including two anal pores
• Nervous system in the form of a nerve net
• Tentaacles usually present with adhesive structures called colloblasts
• Eight rows of ciliary bands, called comb rows, for locomotion
• PLACOZOA

  • Simple nonparasitic animals.

  • The outer body consists of (dorsal) simple epithelium, which encloses a stellate cells resembling the mesenchyme. nonciliated glandular cells.

  • The ventral epithelium is composed of monocilated cells and

  • It feeds by secreting digestive enzymes into organic detritus.

  • Trichoplax reproduces asexually, thru budding
• ACOELOMORPHA

  • Triploblastic and acoelomate.

  • Mostly free-living in marine sediments.

  • They have a simple pharynx, incomplete gut, and mesodermal muscle cells.

  • Sense organs include statocysts and ocelli.

  • Reproduction is either by asexual fragmentation or by internal fertilization by monoecious pairs.

  • No excretory or respiratory structures.

  • Radial arrangement of nerves in their elongated body