Invertebrate Diversity 1 Flashcards
What are Invertebrates?
Animals that are not chordates.
34 of 35 phyla are Invertebrates
Animal Biodiversity
95% of animal species are invertebrates
85% are arthropods of animals
75% of animal species are insects of animals
35% are beetles of animals
Important evolutionary characters
- symmetry (asymmetric, radial & bilateral)
- tissue layers (diplo versus triploblastic)
- true tissues (muscles and neural)
- digestive tract (incomplete versus complete)
- circulatory system (open, closed, absent)
- Coelm (acoelomate, pseudocoelomate, coelomate)
Evolution of metazoan
all animals.
primitive animals were asymmetric and diploblastic with no true tissues (e.g. no muscle, nervous system, digestive system, etc).
Phylum Porifera
Sponges.
- Asymetric, diploblastic
- No true organs
- suspension feeders
- Unique structures and cells
- spicules
- choanocytes
- Diplobastic
Phylum Porifera:
Unique structures and cells:
Spicules
give rigidity
– made of calcium carbonate or silica;
- provide structural support
- effectively forms an exoskeleton
Phylum Porifera:
Unique structures and cells:
choanocytes
collar cells, amoebocytes
- collar cells beat(forces water in and out = particulate matter) and bring food in - amoebocytes digestive part - strong flow of water(remember dye experiment) = incredibly efficient
Phylum Porifera:
Unique structures and cells:
Diplobastic
2 layers separated by gelatinous mesohyl
Evolution of Eumetazoans
animals with true tissues; all animals except sponges
First eumetazoans have a rudimentary nervous and digestive system, contractile tissues, and radial symmetry.
Phylum Cnidarian
corals, jellyfish and hydras.
- Radially symmetric, diploblastic
- Two distinct body plans (medusa & polyp)
- Rudimentary Digestive tract / circulatory system called gastrovascular cavity
- Very inefficient
- Nervous system – nerve net & ocili
- muscle-like structures
- Cnidocytes contain nematocysts
- The cells that sting you
- Offensive or defensive depending
- Medusa uses it as offensive to capture prey
- Nematocysts are thread like than go into victim and inject the poison
Box jelly
Cnidarian
the deadliest animal in the world.
- In Australia - Hand sized but has enough venom to kill 60 people
Evolution of Bilateral symmetry and triploblastic tissues
Three major bilateral animal groups
- Deuterostomes - see previous lecture - Lophotrochozoa - it's complicated…don’t worry about it. - Ecdysozoa - animals that molt an exoskeleton (i.e. ecdysis)
Evolution of triplobastic tissues allows evolution of coelom
LOPHOTROCHOZOA
Platyhelminthes, Rotifera, Mollusca and Annelida
Phylum Platyhelminthes
flatworms; e.g. tapeworms, flukes, planeria.
- Incomplete gut(in category with a gut)
- No circulatory system(in category with circulatory )
- Bilateral, triploblastic, acoelomates
- Cephalization - evolutionary trend that concentrates nervous tissue to one end
- It has a head
- close proximity to each other = faster reaction time
- all sensory organs close together
- Can be free swimming or parasitic
Phylum Platyhelminthes:
Flatworms Reproduction
Flatworms are hermaphroditic but don’t want to get pregnant and spend more resources on eggs and housing
- Thus penis fencing
- Whoever shoots first wins
- Father has less energy requirements
- Highlight sexual conflict
o Biological objectives of males and females does not coincide
Phylum Rotifera
wheel bearers – small water based
- Complete gut
- Alimentary canal
- No circulatory system
- Corona - ciliated discs for feeding
- Parthenogenetic - asexual
- some species produce non-feeding males.
- Literally the male has no mouth
- It reshuffles the genome via sex and dies
- some species produce non-feeding males.
Cephalization
evolutionary trend that concentrates nervous tissue to one end
- It has a head - close proximity to each other = faster reaction time - all sensory organs close together
Alimentary canal
Complete gut(separate mouth and anus)
Phylum Mullusca:
Unique characters
- 3 main parts: Foot, visceral mass, mantle (CaCO3 shell)
- foot = locomotion
- mantle = secretes the CaCO3 shell
- visceral mass = location of all internal organs(mesoderm encased)
- radula – feeding apparatus
- scraping device that rips up algae on floor
- Range of cephalization and nervous systems
Phylum Mullusca:
Classes
- Polyplacophora
- Gastropoda
- Bivalvia
- Cephalopoda
Phylum Mullusca:
Classes:
Polyplacophora
chitons – many plates
- 8 plates; live on intertidal rocks; scrape algae - radula scrapes algae
Phylum Mullusca:
Classes:
Gastropoda
Most have spiraled shells
- e.g. snails, conchs and whelks - torsion - 180 degree twisting of visceral mass - mouth and anus are next to each other(only one opening in a shell)
Phylum Mullusca:
Classes:
Bivalvia
clams, oysters, mussels and scallops
a. hinged shell with adductor muscles
Phylum Mullusca:
Classes:
Cephalopoda
squid, octupi
a. Means "head-foot” b. no shell (except nautilus) c. active hunters d. learning and complex behavior
Blue Ringed Octopi
Phylum Mullusca:
Classes:
Cephalopoda
Deadliest octopus in the world.
Australia
Phylum Annelida
segmented worms
- Complete gut
- Closed circulatory
- Some cephalization
- Some possess parapodia - lateral feet
When you have multiple redundant(segmented) system natural selection can play with it.
Diversifyication/mutations.
Segmented systems and natural selection
When you have multiple redundant(segmented) system natural selection can play with it.
Diversifyication/mutations
Hagfish
The hagfish is classified with chordates but it actually does not have a vertebra
- The term invertebrate is not 100% accurate
Polyp VS medusa
Phylum Cnidarian
polyps(anchored to ground) and medusa(swimming)
when you have a very simple organism you don’t need a circulatory system because all cells are interacting with the environment
Circulatory system gets nutrients to our cells and waste products out of cells when not touched the environment
o Can have mesoderm and still not have a circulatory system
Must be thin though
Alimentary canal
Complete digestive track from mouth to anus.
Asexual populations are female
Asexual populations are female
Acoela and Platyhelminthes do not have _______.
complete digestive tracks
- Have a gastrovascular cavity
Open VS closed circulatory system
Open has a heat that pumps fluid through tubes BUT the tubes are not connected to anything
o Blood coats everything and eventually makes it back to the heart
Arthropods and mollusk
o Blood leaves the network of tubes
Closed has heart that pumps through tubes through capillary beds
o Recaptures in the same system and back to heart
Never leaves the network
