Porifera And cnidaria Flashcards
(107 cards)
Heterotrophic
Eating other organic molecules
What is necessary to be considered an animal?
Multicellular, eukaryotic, heterotrophic, lacks rigid cell walls.
Metazoans
Multi cellular animals
What is the advantage of being multicellular
Can reach a greater size
What is the advantage of a greater size
Cheaper to move and maintain homeostasis
Cellular specialization
Each cell takes on its own job
Interdependence
Cells must depend on each other for survival.
What is the danger of interdependence
If one kind of specialized cell dies off the organism may not be able to survive.
Parazoa
Includes only phylum Porifera and placozoa
Eumetazoa
All other animals, the ones we typically think of.
Mesozoa
20-30 celled creatures, cells arranged in two layers. Parasitic, work like animals.
Characteristics of mesozoa
Minute, ciliated, wormlike. Very small, all are parasitic in marine animals.
Rhombozoa
Live in the kidney of octopi and cuttlefish
Orthonectids
Parasite of invertebrates like sea stars. Have sexual and asexual stages.
Plasmodium
Part of the asexual reproduction of the orthonectids. Multi nucleated mass which divides to create makes and females.
Why are mesozoans important in the phylogeny of other animals?
They’re considered to be the missing link between unicellular and multicellular animals.
Placozoa
Contains a single species, trichoplax adhaerens.
Describe the trichoplax adhaerens
Plate like body, no symmetry, no organs or systems. Have dorsal epithelium of cover cells and shiny spheres. Ventral epithelium has monociliated cells and nonciliated gland cells.
Trichoplax adhaerens feeding behavior
1) glide over prey
2) shoot digestive enzyme on prey
3) absorb
Porifera
Sponges, pore bearing
What is the evolutionary advantage of sponges?
Extreme multicellularity, so they can get really big.
Symmetry of sponges
Asymmetrical, some radial
Habitat of sponges
All aquatic, the majority marine
Locomotion of sponges
Sessile, some can swim