Invertebrates Lecture 2: Introduction to animals 2 (sponges) Flashcards
What is Embryonic Development?
Fertilization (sperm with egg) –> Zygote (diploid cell) –> Embryo (young animal)
What are the major processes during embryonic development?
- Cleavage: mitotic cell division
- Gastrulation: in-folding to form embryonic tissue layers
- Cellular differentiation: cells become specialized
What is the Blastocoel?
What is the Archenteron?
- the “old gut”
- digestive space (gut cavity)
What is the Blastopore?
Is what turns into the mouth in protostomes (invertebrates) and the anus in deuterostomes (vertebrates)
What are the three germ layers and what are their functions?
- Ectoderm (“outer skin”): epidermis, nervous system, the first barrier of protection
- Endoderm (“inner skin”): digestive and respiratory tracts
- Mesoderm (“middle skin”): most internal organs like muscles, skeletal system and part of the gonads
What does diploblastic mean?
an organism with 2 germ layers (two buds)
What does triploblastic mean?
an organism with 3 germ layers (three buds)
- the mesoderm is only in triploblastic organisms
What are the three types of symmetry in organisms?
- Asymmetry
- Radial symmetry
- Bilateral symmetry
What is asymmetry?
an organism that has no symmetry like sponges
What is Radial symmetry?
the body of the organism can be split into equal halves from many angles
What is bilateral symmetry?
when a single axis between the eyes splits the body of the organism into equal halves
What does porifera mean?
pore bearing
What are the characteristics of sponges?
- earliest animals to appear in fossil record (700 MYA)
- sessile as adults, motile as larvae (dispersal)
- primitive features (inherited from common ancestor) and specialized cells but no tissue or organs
- endoskeleton (short sharp rods called spicules)
What is the anatomy of a sponge?
