Download Week 8 (Oct. 14-18, 2013) Follow

Week 8: Animal Evolution & Development
Follow Along Sheet
What is an Animal?
 Members of Kingdom Animalia are:
• Eukaryotic and primarily multicellular
• Heterotrophic
• Largely exhibit motility
 Two unique types of tissues are found only in animals:
o _______________________ Tissue
o _______________________ Tissue
 Most animals reproduce sexually.
o _______________________ stage usually dominant in life cycle.
Reproduction and Development
 Fertilization occurs when a small flagellated sperm (n) fertilizes
a larger, non-motile egg (n), forming a _____________________
_______________________ (2n).
Cleavage
 A series of rapid cell divisions by ____________________ and
cytokinesis.
 The number of cells increases while the total surface area of the
embryo remains the same.
Cleavage Development
 Early cleavage division in ________________________ is radial. E.g.
humans
 Early cleavage division in _________________________ is spiral. E.g.
molluscs
Gastrulation
 The process in which the invagination of the blastula creates the
_________________________________.
 The opening of the newly formed cavity is called the
_________________________________.
 The germ layers, now present in the gastrula, develop into
________________ _________________ ____________________.
Zygote to Gastrula
Animal Diversity
Animals are classified by four main attributes of their body plans:
1. Tissues
2. _______________________
3. Body Cavities
4. ________________ _________ _________________________
Tissues
Groups of cells that have a __________________________, specialized
function
 Parazoa
o Lack true tissues
o Most are _____________________________________
o Example: Phylum Porifera (Sponges)
 Eumetazoa
o Have _________________ tissues
o Examples include all other animals
Symmetry
Imaginary planes create ____________________ images.
1. Bilateria
 Exhibits bilateral symmetry
 _________________________________ - 3 germ layers:
o Endoderm
o _______________________
o Ectoderm
 Examples include:
Every phylum after Phylum Ctenophora
2. Radiata
 Exhibits radial symmetry
 _____________________________ - two germ layers:
• Endoderm
• Ectoderm
 Examples include:
o Phylum Cnidaria
o Phylum Ctenophora
Body Cavity
1. _________________________ - lack a body cavity altogether.
o _________________________ (flatworm) is an example of an
acoelomate.
2. __________________________ - body cavity partially derived from
mesoderm.
o __________________________ is an example of a
pseudocoelomate.
3. _________________________ - those with a true coelom derived
completely from mesoderm
o ____________________________ is an example of a coelomate.
Mesoderm Development
 Between the ectoderm and the endoderm, a coelom formed
by introducing a gap surrounded by mesodermal cells at the
base of the gastrula exhibits _____________________________________
development.
 A coelom formed by “pinching off” a portion of the endoderm
that eventually develops into mesoderm exhibits
________________________________ development.
Fate of Blastopore
 Bilateral organisms can be further classified by the presence
of a body cavity, and then further subdivided according to the
fate of their ________________________________.
1. ________________________________ - mouth develops from
blastopore.
Examples: Octopi, Earthworms, and Insects
2. _________________________________ - anus develops from blastopore,
mouth develops from second opening.
Examples: Sea Urchins and Mammals