Porifera + Cnidaria Flashcards
What are porifera and some of their features?
Basal animals without true tissues; sponges
- marine and sessile
- no organs or internal systems
How do porifera get structural support?
Spicules - tiny silica or calcium carbonate rods
Spongin - fibrous collagen-protein network
What are the 4 cell types of Porifera?
Choanocytes, amoebocytes, porocytes, epidermal cells
What cells line the spongocoel and generate water currents by beating their flagella. What else do they do?
Chonaocytes (collar cells).
- capture suspended food particles
- deliver O2 and nutrients and remove CO2 and waste
What cells are mobile and found in the mesohy transporting nutrients to other cells. What else do they do?
Amoebocytes.
- produce materials for spicules
- differentiate into other cell types as needed
What cells are tubular and make up the pores of a sponge?
Porocytes
What cells form the outer layer of tightly packed cells
Epidermal
What is the mesohyl and what does it do?
Gel-like non-cellular matrix separating the epidermis and choanocyte layer.
- provides structure and support via skeletal elements deposited by amoebocytes
How do sponges feed?
Suspension feeding
- Water is drawn in via flagella through ostia into the spongocoel and out the osculum
- Collar cells extract food particles using microvilli whoch are engulfed via phagocytosis and digested
- Amoebocytes may transfer nutrients to other cells or use them to create structural elements
What are the reproductive structures of sponges like?
Hermaphrodites which can’t self-fertilize
- Eggs develop from modified amoebocytes
- zygote develops into motile, ciliated larvae within mesohyl
How do sponges reproduce?
Asexually - fragmentation and budding
Sexually
- Eggs produced by modified amoebocytes in mesohyl of ‘female’ sponge
- sperm produced by modified choanocytes in ‘male’ sponge
- sperm released through osculum
- choanocytes of female sponge trap sperm cells which are delivered to eggs via ameobocytes
- internal fertilization and development occurs
Sponge lifecycle from larvae?
Larvae develop in water and eventually settle and attach to solid substrate and become sessile
How do sponges interact with the environment?
- clean water via suspension feeding
- form symbiotic mutualisms with algae in photic zones
- may be harvested for bath and art
- produce toxic chemicals to avoid predation providing a safe space for small organisms
Features of Cnidarians?
- sessile and motile marine organisms
- jellyfish, sea anemones, corals
- radially symmetrical, diploblastic body plans
Cnidarians have a sac-like body with a central _____________ _______. They have a single opening which functions as a _____/______.
gastrovascular cavity, mouth/anus
What are the layers in a cindarian?
An outer epidermis is derived from the ectoderm.
Inner gastrodermis derived from endoderm and lines gastrovascular cavity.
Separated by mesoglea - middle jelly
How do Cindarians capture prey?
stinging tentacle with cnidocytes surround the opening
- cnidocytes have nematocysts which deliver stinging toxins to immobilize prey
- tentacles move immobilized prey to gastrovascular cavity
How does gas exchange occur?
Diffusion across epidermis
Lifestyle of polyp vs medusa
Sessile polyp attaches to substrate with oral end exposed upwards.
Motile medusa moves freely through the water via a hydrostatic skeleton, oral end downwards
What are the 3 types of Medusozoas?
Hydrozoans
Scyphozoans
Cubozoans
Hydrozoan lifestyle?
- alternate b/w polyp and medusa forms
- polyp is sessile, reproduces via budding
- medusa are produced via budding but reproduce sexually
- alternate b/w sexual and asexual, both 2n
Scyphozoans/Cubozoans lifestyle?
- predominant medusa stage
- use hydrostatic skeleton to move via contraction-pulsation of body
- cubozoans have cnidocytes
What are Anthozoans?
- corals and sea anemones
- only polyps, asexual reproduction
Coral lifestyle?
- form colonies via budding or fission
- gain nutrition via symbiotic algae
- hard exoskeleton of calcium carbonate
- reef-building organisms
