Lecture 5 - Cnidaria Flashcards
Describe the formation of a gastrula from zygote.
- zygote becomes hollow develops into blastrua
- new cavity (gut) forms in blastrua develops into gastrula
- 2 cell layers: endoderm and ectroderm (diploblast)
What are animals with two germ layers known as?
Diploblasts
What does the endoderm facilitate?
Feeding
What does the ectoderm facilitate?
Sensory, procetion and food capture
What do the ectoderm and endoterm both facilitate?
Respiration, excretion, movement and reproduction
What are the two morphologies of cnidaria?
Medusa and polyp
What type of symmetry do cnidarians have?
Radial Symmetry
What is the gastrovascular cavity?
- the blind gut formed inside the body
- medusa forms have mandubrium for feeding
What is the defining feature of cnidarians?
Cnidocytes
What are cnidocytes?
- specialized cells found only in cnidarians
- “one-time use” and can fire nematocytes to sting prey
- located in between epitheliomusclar cells
Describe the firing process of nematocytes.
- located in the operculum
- cnidocil senses touch which can cause firing
- tension or osmotic pressure from water can cause firing
Describe the nature of water inside the operculum of the cnidocyte.
Salty AF
What are the two forms of hydrozoa?
Hydra and Obelia
Describe reproduction in hydra.
- atypical reproduction
- asexual: budding and regeneration
- sexual: sperm is released to ovary at low temperatures
- eggs hatch at warmer temperatures
Describe reproduction in obelia.
- typical reproduction
- colonies produce free-swimming medusa buds
- medusa buds release egg and sperm
- develops into free-swimming ciliated planula larvae
- settles to form new colony
