Animals are Multicellular
Body Plans
Diversification of Animals
Animals are heterotrophs that ingest their food
Cell Structure and Specialization
Animals are multicellular eukaryotes
Cells are supported by structural proteins like collagen INSTEAD OF CELL WALLS (PLANTS)
Nervous and muscle tissue are defining characteristics unique to each animal
Tissues are groups of similar cells that act as a unit to perform a specific function
Reproduction and Development
Most animals produce sexually with a DIPLOID DOMINANT life cycle
when sperm fertilizes the egg, the zygote undergoes rapid cell division (cleavage)
Cleavage leads to the formation of a multicellular, hollow bastula
Bastula undergoes gastrulation, forming a gastrula with different embryonic tissue layers
Animals have at least one larval stage
Larva is a sexually immature and morphologically different from the adult; undergoes metamorphosis to become a juvenile
juvenile resembles an adult but isnt sexually mature
Body plan is a set of morphological and developmental traits
some body plans have been conserved while others have changed alot over evolution
Symmetry
Bilateral Symmetry
Radial Symmetry
have top and bottom but DO NOT have a front/back or left/right
dorsal/ventral(top/bottom), right/left, anterior/posterior(front/back)
have sensory equipment in their anterior(front)
are drifting/weakly swimming animals
move actively and have central nervous system
Tissues
tissues are collections of specialized cells isolated from other tissues by membranous layers
during development, 3 germ layers create tissues and organs of animal embryo
Ectoderm
Endoderm
Mesoderm
animal classification based on tissues
Triploblastic: have endoderm, ectoderm, and mesoderm
Diploblastic: only have ectoderm and endoderm
all bilaterally symmetrical animals are triploblastic
include cnidarians
germ layer covering the embryo's surface
innermost germ layer and lines the developing digestive tube (archenteron)
muscle layer in between ectoderm and endoderm
Body Cavities
True body cavity is called a coelom and is completely lined by MESODERM. (most triploblastic animals have a body cavity)
Psuedocoelomates
Acoelomates
Coelomates
Possess a true coelom
Body cavity that has one side lined by mesoderm and the other by endoderm
No body cavity
Function of Body Cavities
fluid acts like a skeleton where muscles can work against
enables internal organs to grow and move independently of outer body wall
fluid cushions suspended organs
Grades
Refer to organisms that have similar body plan (coelomates and psuedocoelomates)
share key biological features
not a CLADE
Protosome and Deuterostome Development
Protosome Development
Deuterostome Development
Fate of Blastopore: blastopore becomes the mouth. (blastopore forms during gastrulation and connects the archenteron to exterior of gastrula)
Cleavage: Spiral and determinate
developmental fate of embryonic cells is determined early in development
Coelom Formation: Splitting of solid masses of mesoderm forms coelom
Coelom Formation: mesoderm buds from the wall of the archenteron to form the coelom
Fate of Blastopore: blastopore becomes the anus. (blastopore forms during gastrulation and connects the archenteron to the exterior of the gastrula
Cleavage: radial and indeterminate
Indeterminate cleavage makes identical twins and embryonic stem cells possible
indeterminate cleavage, each cell in the early stages of cleavage retains the capacity to develop into a complete embryo
5 Important points about the relationships among living animals
phylogenies are now based on a comboniation of
Eumetazoa (true animals) is a clade of animals with tissues
Most animal phyla belong to the clade Bilateria
Sponges are the sister group to all animals
All animals share a common ancestor
3 major clades of bilaterian animals
Lophotrochozoa
Ecdysozoa
Dueterostomia
includes both vertebrates an dinvertebrates
only contain intervebrates; secrete their external exoskeletons through ecdysis
have a feeding structure called lophophore; they have a developmental stage called trochophore larva. consist of only invertebrates