lecture 2 Flashcards
How do sponges, cnidarians, ctenophores and flatworms differ with respect to body symmetry and presence and number of tissue layers?
Sponges:
BS: asymmetrical/ irregular
T: no tissues
Cnidarians and Ctenophores:
BS: Radial symmetry
T: diploblastic
Flatworms:
BS: bilaterial
T: triploplastic
How do sponges, cnidarians, ctenophores and flatworms gather food from their environments and how do the methods differ from each other?
Sponges: filter-feeders. The choanocytes capture food particles when they get trapped by their mucus and then they eat via phagocytosis
Cnidarians and ctenophora: Acoelomate. Gastrovascular cavity (incomplete gut).
Cnidarians also use phagocytosis and prey capture using their cnidocyte and nematocyte
Flatworms: Acoelomate. Gastrovascular cavity (incomplete gut)
what organs systems are present in free-living flatworms (Turbellaria)?
only a digestive system (incomplete gut)
no circulatory or respiratory system
which organ system is absent in tapeworms (Cestoda)?
through evolution lost their mouths and digestive systems and absorb nutrients directly through their body wall
what do rotifers have that platyhelminths don’t?
- complete digestive tract: mouth and an anus. (food only travels in one direction= increased efficiency)
- pseudocoelomate
which major groupings of animals defined on the basis of morphological characters have been confirmed by molecular sequence studies?
. idk
Parazoa (no tissues).
what phylum is under here?
Porifera (sponges)
another word for openning
osculum
Porifera don’t have tissues but they do have 3 different cell layers namely
Layers arrange around spongocoel:
- Inner layer = choanocyte
- Mesohyl (with spicules that provide support and amoeboid cells)
- outer cover= flattened cells of pinacodem
Eumetazoans with radial symmetry: Radiata have 2 phyla
- Cnidaria
2. Ctenophora
cnidarian life/ reproductive cycle. They can either be …………..(2)
only polyp or medusa , some switch between both
what are the 4 lineages of Cnidaria and are they polyp,medusa or both
- Hydrozoa: both
- jellyfish (Scyphozoa) and box jellyfish (Cubozoa): Medusa (release gametes into water where fertilisation takes place)
- Anthozoa : polyps
2 types of Anthozoa
- corals
2. sea anemones
scientific name for flatworms
platyhelminthes
4 types of platyhelminthes
- turbellaria
- trematoda
- monogenoid
- cestoda
what type of body symmetry do sponges exhibit
dont exhibit any kind of body symmetry
how does the sponge gather food from its environment
gathers food from its environment by drawing water into its body through numerous small pores and harvesting particulate matter from the water with its choanocytes, or collar cells
how do cnidarians capture, consume, and digest their prey
capture prey by stinging it with their nematocytes and using their tentacles to pull it into their mouth
which group of cnidarians has only a polyp stage in its lifecycle
the anthozoans, including sea anemones and corals
what do ctenophores eat, and how do they collect their food
microscopic plankton in sticky filaments on their 2 tentacles, which are then drawn across the mouth
what organ systems are present in free-living flatworms (tubellaria) (4)? which of these organ systems is absent in tapeworms (cestoda)(1)
Free living flatworms have digestive, excretory, nervous and reproductive systems.
Tapeworms lack a digestive system