Chap. 32 Flashcards
tissues
groups of similar cells that act as a functional unit
cleavage
after fertilization forms a zygote, a succession of mitotic cell divisions without cell growth between the divisions
-animal sexual reproduction
blastula
cleavage leads to the formation of a multicellular embryonic stage called a blastula, which in many animals takes the form of a hollow ball
gastrulation
the layers of embryonic tissues that will develop into adult body parts are produced creating a Gastrula
- after blastula
larva
a sexually immature form of an animal that is morphologically distinct from the adult, usually eats different food, and may even have a different habitat than the adult
metamorphosis
Animal larvae eventually undergo metamorphosis, a developmental transformation that turns the animal into a juvenile that resembles an adult but is not yet sexually mature.
defining characteristics of animals
muscle and nerve cells are central to the animal lifestyle.
collagen
proteins external to the cell membrane that provide structural support to animal cells and connect them to one another
Hox genes
regulate the development of
body form
-make sure right body parts form in the right places
choanoflagellates
the closest living relatives of animals
Ediacaran
early group of mostly soft-bodied multicellular eukaryotes
-early animal fossil record
Cambrian explosion
(535–525 million years ago) marks the earliest fossil appearance of many major groups of living animals
-Ediacaran life-forms declined
bilaterians
most of the fossils from the Cambrian explosion are of bilaterians
-have the following
traits:
* Bilaterally symmetric form
* Complete digestive tract
* One-way digestive system
Arthropods
were the first animals to adapt to terrestrial habitats
Paleozoic Era (541–252 Million Years Ago)
cambrian explosion
Mesozoic Era (252–66 Million Years Ago)
Coral reefs emerged, dinosaurs were the dominant terrestrial
vertebrates, The first mammals emerged, Flowering plants and insects diversified
Cenozoic Era (66 Million Years Ago to the Present)
mass extinctions of both
terrestrial and marine animals, rise of large mammalian herbivores
body plan
a particular set of morphological and developmental traits that are integrated into a functional whole
radial symmetry
the type of symmetry found in a
flowerpot
- have not and bottom but no front, back, left, or right.
bilateral symmetry
The two-sided symmetry of a shovel
-humans
bilateral symmetry different sides
dorsal (top) side and a ventral (bottom) side
* A right and left side
* Anterior (front) and posterior (back) ends
whatre the germ layers
Ectoderm, Endoderm,
Ectoderm
the germ layer covering the embryo’s surface
Endoderm
the innermost germ layer and lines the developing
digestive tube, called the archenteron
Diploblastic animals
have only ectoderm and endoderm
* These include cnidarians and a few other groups
Triploblastic animals
have ectoderm and endoderm and also have an intermediate tissue layer called mesoderm
mesoderm
fills much of the space between the ectoderm and endoderm
All bilaterally symmetrical animals have…. and are called….
- a mesoderm
- triploblastic
body cavity
a fluid- or air-filled space located between the digestive tract (endoderm) and the outer body wall (ectoderm)
coelom
a body cavity that forms from tissue derived from mesoderm
coelomates
Animals possessing coeloms are sometimes called coelomates
hemocoel
a body cavity that forms between the mesoderm and endoderm
pseudocoelomates
Animals with only a hemocoel once were called pseudocoelomates
acoelomates
triploblastic animals lack a body cavity altogether
Protostome development
develop mouth first then anus
-spiral and determinate development
Deuterostome development
develop anus first then mouth
-humans
-radial and indeterminate development
body cavity functions
- Fluid cushions the suspended organs
- Fluid acts like a skeleton against which muscles can work
- The cavity enables internal organs to grow and move
independently of the outer body wall
determinate cleavage
development rigidly casts (“determines”) the developmental fate of each embryonic cell very early
indeterminate cleavage
meaning that each cell produced by early cleavage divisions retains the capacity to develop into a complete embryo
archenteron
During gastrulation, an embryo’s developing digestive tube initially forms as a blind pouch, the archenteron, which becomes the gut
deuterostome coelom development
the mesoderm buds from the wall of the archenteron to form the coelom
protostome coelom development
the splitting of solid masses of mesoderm forms the coelom
blastopore
forms during gastrulation and connects the archenteron
to the exterior of the gastrula
what does the blastopore become in protostome vs deuterostome
- In protostome development, the blastopore becomes the mouth
- In deuterostome development, the blastopore
Five important points about the relationships among living animals are….
- All animals share a common ancestor
- Sponges are the sister group to all other animals
- Eumetazoa (“true animals”) is a clade of animals with tissues
- Most animal phyla belong to the clade Bilateria
- There are three major clades of bilaterian animals, all of which are
invertebrates, animals that lack a backbone, except Chordata, which
includes vertebrates, animals with a backbone
