Lecture 16: Protostomes 1 Flashcards
How many animal phyla are protostomes out of 30?
22/30 are protostomes
What 3 important ecological roles do protostomes fill?
- Live in virtually every aquatic and terrestrial havbitat
- Can be detritivores, herbivores, or carnivores
- Importance extends to human health
What are the 2 major subgroups of protostomes?
- Lophotrochozoa
- Ecdysozoa
What 3 things are unique to protostomes compared to deuterostomes?
- Embryonic development of mouth before anus during gastrulation
- Inability of isolated early embryonic cells to develop into complete embryo
- Formation of coelom by splitting of blocks of mesodermal cells
Where do fossils indicate protostome lineages originated?
The ocean.
Protostomes made the transition from water to land multiple times
What is adaptive radiation?
A period of rapid speciation.
What is the benefit of the land transition?
For protostomes/land plants?
Water to land transitions open up entirely new habitats and new resources to exploit.
Protostomes:
- Transition to land coincided with adaptive radiation of plants on land
Land plants:
- Thrived due to more sunlight and CO2
What 3 adaptations must protostomes have to make the land transition?
- Exchange gases with air
- Avoid drying out
- Hold up their bodies under their own weight
What is the importance of protostomes?
- Major direct source of food (seafood)
- Provide ecosystem services (pollination)
- Some damage crops (pests)
- Some produce materials (silks/pearls)
- Cause/transmit human diseases
- Include drosophila and roundworm
What are the key innovations of roundworms and earthworms?
- High surface-area-to-volume ratio
- Increases efficiency o f gas exchange across their body surface in moist environments
What are the key innovations of arthropods and mollusks?
- Have gills or other respiratory structures inside body
- Minimizes water loss when moving onto land
What are the key innovations of insects?
Insects evolved a waxy layer to minimize water loss from body surface.
- If environment dries, openings to respiratory passages can be closed
What are the key innovations of dessication-resistant eggs?
- Evolved repeatedly in populations that made transition to life on land
- Insect eggs have thick membrane that keeps in moisture
- Snail and slug eggs have thick shell that retains water
What are compartmentalized body plans and who has them?
Protostomes have compartmentalized body plans in which:
- bodies are divided into different regions with different functions
What are lophotrochozoans?
Lophotrochozoans are one of the major subgroups of protostomes. They are a monophyletic group with 13 phyla that includes rotifers, flatworms, annelids, and mollusks.
- could have a lochophore
- could have a trochophore
- grow continuously/incrementally
- spiral cleavage
What is a lophophore and a trochophore?
A lophophore is a feeding structure found in 3 phyla and a trochophore is a type of larva found in many of the phyla.
The lophophore is a specialized structure that rings mouth of these animals and functions in suspension feeding.
The trochophore larvae has a ring of cilia that functions in sweeping and sometimes feeding.
Trochophore larvae occurs in animals that undergo indirect development:
- live in different habitats and eat different foods
- originated early evolution of lophotrochozoans
What is spiral cleavage?
Lophotrochozoans undergo spiral cleavage, which is when cells divide at oblique angles and spiraling patterns of cells in blastula results
What two traits are unique to ecdysozoans?
- Cuticle and exoskeleton
- protect animals from predators
- provide structure for muscle attachment
What is molting?
Ecdysozoans grow intermittently by molting: shedding of the soft cuticle or exoskeleton.
Once animal molts: fluid expands body and larger exoskeleton forms.
Sometimes morphological transformations occur during these molts
