Animal diversity questions Flashcards
What is a “metazoan”?
means animal or (later/ after animal)
What are the defining characteristics of animals?
Eukaryotic
Multicellular-except gametes (sperm and egg)
heterotrophic
All individuals are diploid; Only gametes are haploid
No cell walls(use extracellular structural proteins instead
in particular collagen, the most abundant protein in your body, 1/3 of all your protein)
ingest their food then digest
Compare digestion of animals and fungi
Are fungi more closely related to animals or plants?
Both are heterotrophs
Animals ingest food bring in and then digest using enzymes
Fungi (digest food externally and take in after)
are more closely related to animals than plants have cell walls
How do plants obtain nutrition?
autotrophic eukaryotes- capable of making their own food- thru photosynthesis
What is the Haploid stage?
composed of gametes (egg and sperm) that are produced by meiotic division by the diploid stage
Cells of haploid stage don’t undergo further division
How does reproduction and development start?
The sperm fertilizes the egg forming a diploid zygote
Describe the animals developmental cycle
- The zygote of an animal undergoes mitotic cell division called cleavage
- An eight cell embryo is formed by 3 rounds of cell division
- Cleavage produces a multicellular stage called a blastula
- Most animals undergoes gastrulation
- The pouch formed by gastrulation called the archenteron opens to the outside via the blastopore
- The endoderm of the archenteron develops into the tissue lining the animals digestive tract
List the evidence of shared ancestry between the animals and choanoflagellates
- Choanocyte cells of sponges look like choanoflagellates showing that the molecular evidence is true that animals evolved from choanoflagellate like animals
- collar cells that are similar have been found in echinoderms flatworms and cnidarians but not in non choanoflagellate animals
- DNA evidence that shows that animals and choanoflagellate are sister groups and signaling and adhesion proteins which had been only found in animals were found in them too
What are the characteristics of radial symmetrical animals? give examples
Animals are sessile(living attached to a substrate )or platonic
(drifting or weakly swimming such as jellyfish)
Diploblasts are this
Don’t have distinct head region
ex; cnidarians, some anemones
What are the characteristics of bilaterally symmetrical animals? give examples
ex; lobster, mammals arthropods
Has 2 axes of orientation: front to back and top to bottom
Have sensory equipment at anterior end including the nervous system (brain)- called cephalization
More active than radial animals(The central nervous system allows them to coordinate complex movements involved in crawling burrowing flying or swimming )
Triploblastic
What animals lack tissues?
sponges have no tissues meaning they have no organs and are asymmetrical
(monophyletic)
What is the function of the Body Cavities of triploblasts?
Structural support
Formation of the internal transport system to supply nutrients
Allow efficient gas exchange
Remove waste
Why is the Hemocoel called a false body cavity?
because there isn’t mesoderm surrounding it completely
What is the function of heomocoel body cavity and fluid ?
Internal circulation
Nutrient transport
Waste removal
Hydrostatic skeleton
What kind of cleavage do Protostomes go through? Deuterstomes?
P- spiral and determinate
d- radial and indeterminate
Compare coelom formation in deuterostomes and protostomes?
Protostomes–the solid masses of mesoderm cells split and form the coelom (coelom opens up inside middle of mesoderm)
Deuterostome development the mesoderm buds from the wall of the archenteron and its cavity becomes the coelom (folds in from mesoderm up at the top of archenteron)
Compare the fate of the blastopore in deuterostomes and protostomes
In protostome development the mouth forms from the blastopore
Deuterostome development- the mouth forms from a secondary opening the blastopore forms the anus
What are sponges considered? why
basal animals
- their lack of body symmetry
- the close resemblance of poriferan cells to slime molds
- their lack of germ layers
- the close resemblance of choanocytes to choanoflagellates
What is the most diverse clade
Bilateria
Bilateral symmetry and 3 germ layers
What are are 3 major clades of bilaterian animals ?
Deuterostomia
Lophotrochoza
Ecdysozoa
How can animals be categorized?
Animals can be categorized by a number of features:(through morphology) Presence of tissues Body symmetry Body segmentation Presence of exoskeleton Embryonic tissue layers Digestive openings Mouth first Presence of body cavity
Which came first, the sponge or the comb jelly?
Sponges did come first Ctenophores: are not a basal animal come between sponges and cnidarians Not always radial Have more cell types than sponges Have a rudimentary nervous system(more complicated than sponges) Similar to cnidarians nervous system Active hunters Called comb jellies- have combs of cilia
What are the defining characteristics of phylum porifera?
High resemblance to certain colonial protists( cellular slime molds)
are sedentary
asymmetric body plan
Are suspension feeders-(have spongocoel and osculum)
Lack tissue but contain many cell types (choanocytes and amebocytes)
body consists of 2 layers of cells
sequentially hermaphroditic
No nervous system( have individual cells that contain much of the machinery of typical animal nerve cells (lot of proteins DNA sequences)
Adults are sessile(permanently attached to something)- larve swim
What do amebocytes do?
Move through the mesohyl
Take up food from surrounding water and from choanocytes digest it and carry nutrients to other cells
Manufacture tough skeletal fibers within the mesohyl
Some fibers are sharp spicules made of calcium carbonate or silica(the exoskeleton) Or flexible protein called spongin
Are totipotent
What does it mean to be totipotent?
characteristic of amebocytes
can transfer into any cell type as needed
What do Choanocytes do?
Pull water in thru the pores
Look similar to choanoflagellates (pre animals single cellular)- support molecular evidence that animals evolved from choanoflagellate like ancestors
Engulf bacteria by phagocytosis
What are the defining characteristics of phylum cnidaria?
The first eumetazoans
only two tissue layers
Most are marine; a few are in fresh water
Only one digestive system opening
diploblastic
radial body plan
gastrovascular cavity(single opening to this cavity functions both as mouth and anus )
Body wall has 2 layers of cells( gastrodermis and epidermis)
2 variations in body plan( polyp or medusa)
Polyps
Ex: hydra and sea anemones
Primary sedentary- but can move
When threatened by a predator some can swim by bending their body column back and forth
Medusa
Moves freely- free swimming jellies
Some exist only as one body plan some have both stages in their life cycle
Are predators that use tentacles arranged in a ring around their mouth to capture prey and push the food into the gastrovascular cavity
Tentacles are armed with batteries of cnidocytes
Medusa
Moves freely- free swimming jellies
Some exist only as one body plan some have both stages in their life cycle
Are predators that use tentacles arranged in a ring around their mouth to capture prey and push the food into the gastrovascular cavity
Tentacles are armed with batteries of cnidocytes
Contain cnidae
What are Medusozoans?
clade of cnidarians (monophyletic)
All cnidarians that produce a medusa are members of this clade
Include jellies box jellies and hydrozoans
Alternate between polyp and medusa life cycle
What are Anthozoans?
clade of cnidarians (monophyletic)
ex; Sea anemones and coral
only occur as polyps
have Exoskeleton
Corals make skeleton of calcium carbonate
Coral reefs are hard external skeletons secreted by certain cnidarians
What are Hydra ?
Freshwater cnidarians
Immortal
Exist only in polyp form but are not sessile- they “walk”
Only a few cell types
Frankenhydra- if you cut 2 they can fuse
Don’t have a mouth- rip body apart to swallow
Which is the biggest subphyla?
Lophotrochozoans phyla contains most pyhla)
Lophotrochozoans phyla include?
Flatworms Rotifers Ectoprocts Brachiopods Molluscs Annelids
Flatworms(platyhelminthes)
Live in marine or freshwater
Have thin bodies that are flattened dorsoventrally
First animals with bilateral symmetry
First animals with 3 embryonic tissue layers
Are protostomes
Undergo triploblastic development- but lack a body cavity
have gastrovascular cavity
Only one digestive opening
Have no organs specialized for gas exchange
Protonephridia
lack circulatory system
True nervous system
describe the Flatworms(platyhelminthes) nervous system?
Paired eyespots Paired anterior ganglia (close to being a brain) Segmented gangia Paired ventral nerve cords Transverse nerve cords
What are examples of platyhelminthes?
Include tapeworms and flukes
What are the benefits of the flat shape of flatworms?
Flat shape places all cells close to water or in their gut
Flat shape maximizes surface area for efficient exchange processes
Where are the nerve cords located on Invertebrates ?
have nerve cords always on ventral side
What are the defining characteristics of Planarians?
type of free living flatworm
Found in freshwater ponds
Move by using cilia on their ventral surface
Nervous system is more complex than cnidarians
Some can reproduce asexually through fission
Sexual reproduction can also occur
Are hermaphrodites
Exhibit extraordinary regenerative ability
important in the study of regenerative medicine
Tapeworms
Adults live mostly in vertebrates
Lack a mouth and gastrovascular cavity(no real digestive system)- absorb nutrients released by digestion in the hosts intestine
Lophotrochozoan named?
Lophophore- a crown of ciliated tentacles that function in feeding
Trochophore larvae- distinctive larvae stage observed in some Lophotrochozoan including some annelids and molluscs
What examples of molluscs?
Ex: snails slug oysters clams octopuses
what is the Second most diverse phlyum of animals ?
molluscs
What are the defining characteristics of molluscs?
Bilateral
triploblastic
protostomes
Complete digestive tract (2 digestive openings) (aka alimentary canal or gastrointestinal tract)
Are soft bodied and secrete a hard protective shell made of calcium carbonate
All have a similar body plan : foot visceral mass and mantle
Open circulatory system (except cephalopods)
Complete nervous system(brains, eyes
Paired ventral nerve cords from brain that go the entire length of the body
Some simpler animals have ganglia that encompasses esophagus(invertebrates)
Shell is not shed does not moult unlike ecdyszoans
They grow by secreting more shell
What is the benefit of a complete digestive tract?
Benefit is that there is one directional digestive tract with specialized regions(multiple things can happen at once)
What are the groups of molluscs?
Chitons
Gastropods (belly foot)
Bivalves (2 doors)
Cephalopods (head foot)
Gastropods
ex- Snails and slugs
Have a mucus gland and animals slides along it
¾ belong to this clade
marine freshwater or terrestrial species
Move very slowly by cilia or foot
Have single spiraled shell into which the animal can retreat when threatened
Bivalves
Are all aquatic
Ex- clams(sedentary) oysters mussels(sessile) scallops (swim and have eyes)
Have a shell divided into 2 halves which are hinged and have powerful adductor muscles drawing them in tightly to protect animals soft body
Have no distinct head and no radula
Have eye and sensory tentacles along the outer edge of the mantle
Mantle cavity of bivalve contains gills that are used for gas exchange as well as feeding
Most are suspension feeders
Cephalopods
Ex: nautiluses cuttlefish squids and octopuses
Are active marine predators
only molluscs with a closed circulatory system
Most advanced and largest eyes
Ammonites
Well developed brain and sense organs
Octopus and squids have no shell (have huge brains)
Don’t have a mantle either
What are the defining characteristics of Annelids
Segmented worms Bilateral triploblastic protostome Complete digestive tract with 2 openings Digestive systems not segmented specialized along the path (elongates as animal develops) Nervous and closed circulatory systems are segmented 2 groups: Errentia and Sedentaria
Why is segmentation good?
Makes development easy because segments just repeat (with some modifications)
How are different segments made?
Hox genes
- determine when and where things grow
Determine where the brain will go intestines etc (where changes in segments grow)