Lecture 11 Pt. 3

Question 1

Enigmatic phylum

Answer 1

• Unique phylum; solely grouped by protostomian and spiralian development
• Approx. 120 extant species

Question 2

Urine filled home of dicyemida

Answer 2

• Only observed lining the renal appendages of cephalopods
  
  • Attached to surface of renal appendages or sac
  • May occasionally swim in the urine

Question 3

Nematogen

Answer 3

• Vermiform embryo forms asexually as axoblasts develop into agamete cells
  
  • Agametes mature in full adults within the host

Question 4

Anatomy

Answer 4

• Acoelomate, no symmetry exists; no differentiated organs
• 8 - 40 outer ciliated somatic cells cover a single long interior axial cell
  
  • Contains polypoid nucleus and intracellular stem cells called axoblasts
• Anterior somatic cells form polar cap
  
  • Two parapolar cells behind cap
• Posterior two cells are the uropolar cells

Question 5

Asexual reproduction

Answer 5

Cytoplasm of the single large axial cell contains intracellular stem cells called axoblasts
- Immature vermiform organisms form when these axoblasts undergo embryo
* First division makes large axial cell and small somatic cell
* Somatic cell repeatedly divides to enclose axial cell
* Axial cell divides unequally, daughter cells engulf by largest one
* Becomes adult precursor
* Attaches to host after swimming through urine

Question 6

Attachment

Answer 6

• Polar cap attaches to renal tubules and crypts of the renal sac
  
  • No harm to host
• Somatic cell and their cilia draw in food from cephalopod urine
  
  • Phago/pinocytosis

Question 7

Phagocytosis

Answer 7

The process by which a cell uses its plasma membrane to engulf a large particle

Question 8

Pinocytosis

Answer 8

A process by which the cell takes in the fluids along with dissolved small molecules