Lecture Exam #3 part 2 Flashcards
are there exceptions to nearly every criteria for distinguishing animals from other life-forms
yes
what defines a group?
several characteristics, taken together
how do most animals reproduce?
sexually, with the diploid stage usually dominating the life cycle
after a sperm fertilizes an egg in animals what happens/
the zygotes undergoes cleavage
rapid cell division
cleavage
what does cleavage lead to the formation of?
a multicellular hollow blastula
what does the blastula undergo?
gastrulation
after the bastula goes through gastrulation what does it form?
a gatrula with different layers of embryonic tissues
characteristics of most animals (5) (MSSTC)
1) mobile
2) use strength
3) use speed
4) use toxins
5) use camaflogue to detect, capture and eat other organism
what is an example of an animal using its traits to its advantage/
the chameleon captures insect prey with its long sticky, quick-moving tongue
what type of nutritional mode do animals have?
they are heterotrophs that ingest their food
what type of cells are animals?
multicellular eukaryotes
what do animal cells lack?
cell walls
what are animal bodies held together by?
structural protein such as collagen
what is unique in animals and is the defining characteristic of animals?
nervous and muscle tissue
groups of similar cells that acts a functional unit. collections of specialized cells
tissues
what do most animals have at least one of?
larval stage
sexually immature and morphologically distinct from the adult. it eventually undergoes metamophasis to become a juvenile
larva
what does a juvenile larva resemble?
an adult, but s not yet sexually mature
what do most animals and only animals have?
hox genes
what do hox genes regulate?
the development of body form
although the hox family of genes has been highly conserved, what can it produce?
a wide diversity of animal morphology
when did the Cambrian explosion occur?
during the Paleozoic era
what marks the earliest fossil appearance of many major groups of living animals?
the cambrian explosion
what are most of the fossils from the cambrian explosion?
bilaterians
what characteristics to the organisms from the cambrian explosion have? (bco)
1) bilaterally symmetric form
2) complete digestive tract
3) one-way digestive system
when did the common ancestor of all living animals live?
between 700 and 770 million years ago
during the neopreterzoic era what did early members of the animal fossil record include?
Edicaran biota
during the neopreterzoic era what evidence was found?
early animal embryos and evidence of predation found in neopreterzoic rocks
what does morphologial and molecular evidence point to?
a group of protists called chaonoflagellates as the closest living relative to animals
what may the protists called chaonglagellates resmeble?
modern chaonoglagellates
several hypothesis regarding the cause of the cambrian explosion and decline of Edicaran biota
1) new predator-prey relationships
2) a rise in atmospheric oxygen
3) the evolution of the hox gene complex
even though animal diversity continued to increase through the Paleozoic what was it punctuated by?
mass extinctions
when did animals begin to make an impact on land?
by 450 million years ago
when did verterbrates make the transition to land?
around 365 million years ago
what do zoologists sometimes categorize animals according to?
a body plan
a set of morphological and developmental traits
body plan
what is true of body plans?
some have been conserved and some have changed multiple times over the course of evolution
two-sided symmetry
bilateral symmetry
characteristics of a bilaterally symetrical animal (3) (DRI)
1) dorsal (top) side and a ventral (bottom side)
2) a right and left side
3) an anterior (front) and posterior (back) ends
what else might a bilaterally symmetrical animal have?
sensory equipment such as brain, concentrated in the anterior end
when did coral reefs emerge and what did they become important as?
mesozoic era becoming an important marine ecological niche for other organisms
what were and what happened to the ancestors of pleisiosaurs
they were reptiles that returned to water
during the Mesozoic era what were the dominant terrestrial vertebrates?
dinosaurs
what emerged during the Mesozoic era?
the first mammals
what diversified during the Mesozoic era?
plants and insects
what can animals be catergorized according to?
symmetry of their bodies or lack of it
animals with no front and back, or left and right
radial symmetry
what are radial animals usuallly?
sessile (dormant) or planktonic (drifting or weakly swimmin)
what are bilateral animals and what do they have that radial animals do not?
often move more actively and have a central nervous system
what did the beginning of the Cenozoic era follow?
mass extinctions of both terrestrial and marine animals
what do the exintctions during the Cenozoic era include?
large, nonflying dinosauras and marine reptiles
what happned to mammals during the Cenozoic era?
they increased in size and exploited vacated elcological niches
what happened o the global climate during the Cenozoic era?
it cooled
what varies according to the organization of the animal’s tissues?
an animal’s body plan
what are tissues isolated from and by what?
other tissues by membranous layers
during development of animals, what gives rise to the tissues and the organs of the animal embryo?
3 germ layers
the germ layers covering the embryo’s surface
ectoderm
the innermost germ layer and lines the developing digestive tube, called the archentron
endoderm
based on early development what can many animals be categorized by?
as having protosome development or deuterostome development
what groups lack tissues?
sponges and a few others
animals that have an ectoderm and endoderm
diploblastic
what does diploblastic animals include?
cnidarians and few other groups
animals have an intervening layer called a mesoderm
triploblastic
what do triploblatic animals include?(3) (FAV)
1) flatworms
2) arthopods
3) vertebrates and others
a body cavity derived from the mesoderm and endoderm
pseudocoelom
what do triploblastic animals posses and what are they called?
a pseudocoelom called pseudocoelmates
what is cleavage in protostome development?
spiral and determinate
what is cleavage in deuterostome development?
radial and indeterminate
with inderminate cleavage what is each cell?
in the early stages of cleavage
what does cellsdeuterostome cleavage in its early stages show?
that it retains its capacity to devleop into a complete embryo
what does intermindate cleavage make possible?
identical twins and embryonic stem cells
what do most triploblastic animals possess?
a body cavity
what is a true body cavity called and what is it derived from?
a coelom and is derived from mesoderm
animals that possess a true coelom
coelomates
what are triploblastic animals that lack a body cavity called?
acoelomates
in protosome development how is the coelom formed?
by the splitting of solid masses of mesoderm
in deuteorstome how is the coelom formed?
the mesoderm buds from the wall of the archentron
what do phylogenies now combine?
morphological, molecular and fossil data
three clades of bilaterian (DEL)
1) deuterostomia
2) ecdysozoa
3) lophotrochozoa
what does dueterstomia include? (3) (HEC)
1) hemichordates (acorn worms)
2) echinoderms (seas stars and relatives)
3) chordates
what does the deuterstomia clade include?
both vertibrates and inverterbrates
when does the blastopore dorm and what does it connect to?
during gastrulation and connect the archentergon to the exterior of the gastrula
what happens to the blastophore in protostome devleopment?
it becomes the mouth
what happens to the blastophore in deuterostome development?
it becomes the anus
5 important points about animal phylogeny that are supported by systemic analysis of morphological characters and recent molecular studies (5) (ASEM3)
1) all animals share a common ancestor
2) sponges are basal animals
3) eumetazoa (true animals) is a clade of animals with true tissues
4) most animal phyla belong to the clade billateria
5) 3 major types of billaterial animals
what do the three major clades of bilaterian animals include?
all invertebrates (lacks back bone) except chordata which are vertebrates (have back bone)
clad of invertebraes that shed their exoskeleton through a process called ecdysis
ecdysozoa
a feeding structure that most lophtrochorozoans have
lophophore
whatdo other lophotrochozoa go through?
a distinct developmental stage called the trochophore larva
a group whose members share key biological features
grade
a group consisting of an ancestor and all its descendents
clade
two grades that regard embryonic germ layers
1) diploblastic
2) trploblastic
what diplobastic include?
ectoderm and endoderm
what does triploblastic include?
ectoderm, mesoderm and endoderm.
3 different grades of colemn
1) pseducolmates
2) colomates
3) acolemates
when determinate and sprial claeavage take place
protosome development
when radical and interminate cleavage take place
duetersome development
having two layers of embryoynic tissue layers, the ectoderm and endoderm
diploblastic
when there is a 3rd layer present, the mesoderm
triploblastic
describe the alternate classifications of acoelomate flatworms that are supported by systems analyses of morphological characters and recent molecular studies
recent research showed that they are basal bilaterians and not members of the phylum platyhelminthes.
what does the fact that recent research showing that acoelomate flatworms are basal bilaterians suggest/
that bilaterians may have descended from a common ancestor that resembled living acoelomate flatworms
how would living acoelomate resemble acoelomate flatworms?
they had a similar nervous system, saclike gut with a single opening and no excretory system
what was the different view that arose based on regarding relationships of annelids and arthropods that are supported by system analyses of morphological characters and recent molecular studies
1) ribosomal genes
2) hox genes
3) dozens of other protein coding nuclear genes
what did the studies about the relationships between annalids and arthropods indicate the 3 major clades are?
1) deuterostomia
2) lophotrochozoa
3) ecdysoszoa
are arthropods and annalids closely related to one another?
no
