invertebrates Flashcards
What are ecdysozoans?
group of animals that grow by ecdysis (moulting)
What is a coelom
Fluid filled cavity that largely acts as a hydroskeleton
Lines with mesoderm and place for gas exchange and internal organs
What are Hox genes
Group of genes common among all animals that designates regions of body plans along head to toe axis
What is Cephalization?
The centralization of sense organs and nervous control at the anterior end of the body. Thus, creating a brain and head.
Protostome
Mouth appears before anus during development of blastopore. Coelom is formed from splitting of mesoderm.
Deusterostomes
First opening during development of blastula forms anus and coelom forms from outgrow of primitive gut.
Lophotrocozoa
-Second largest group after arthropods
-Triploblastic and bilaterally symmetrical
ie, annelids and mollusks
What are the 7 main characteristics of animals
- Eukaryotic
- Multicellularity
- Heterotrophic
- No cell wall
- Motile at some life stage
- Have diploid somatic cells
- Diplontic life cycle
How is multicellularity an advantage?
- Allows organism to grow therefore have a longer lifespan
- Cells carry out specific functions
- Cells are small- better function because there is a high surface area to volume ratio
Types of skeletons
- Hydrostatic (jellyfish, octopus)- limited possibility for attachment
- Exoskeleton- molt
- Endoskeleton
What is the closest living relative to animals?
Choanoflagellates
Proof that animals are monophyletic
- Similar gene sequences
- Similar extracellular matrix
- Unique junctions
Germ layers
- Endoderm (inside)
- Mesoderm
- Ectoderm
Triploblastic vs Diploblastic
Triploblastic= three germ layers Diploblastic= Two germs layers (no mesoderm)
Sponges
- Have endoskeleton (spicules for support)
- Sessile as adults motile larvae
- Filter feeders (choanocytes)
- Can be asexual and reproduce via fragmentation or internal budding (gemmules)
- Can reproduce sexually by being hermaphroditic BUT one at a time- sperm but find another “female” sponge
What is the name for jellyfish, anemones, corals…
Cnidaria