BIOL 1202 : Exam 4 Learning Objectives
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BIOL 1202: Exam 4 Learning Objectives
Ch. 32—An Introduction to Animal Diversity
32.1: Animals are multicellular, heterotrophic eukaryotes with tissues that develop
from embryonic layers.
• The 5 characteristics that combine to define animals are: nutritional mode, cell
structure, specialization, reproduction, & development.
a) Nutritional Mode
▪ Rather than constructing of their own organic molecules, as plants
do, animals ingest them, either by eating other living organisms or
by eating nonliving organic material.
▪ Unlike fungi, animals ingest their food & use enzymes to digest it
w/in their bodies.
b) Cell Structure
▪ Animals are multicellular eukaryotes that, unlike plants & fungi,
lack the support of cell walls.
• Their cell walls receive structural support from a variety of
proteins external to the cell membrane, which connect
them to one another.
o Collagen is the most common of these proteins & is
found only in animals.
c) Specialization
▪ 2 types of specialized cells: nerve cells & muscle cells.
• Organized into tissues (groups of cells that have a common
structure, function, or both).
• Responsible for moving the body and conducting nerve
impulses.
d) Reproduction
▪ Most reproduce sexually w/ diploid stage dominating life cycle.
▪ In haploid stage, meiotic division produces sperm & egg cells.
1. A small, flagellated sperm fertilizes a larger, nonmotile egg,
forming a diploid zygote.
2. Zygote undergoes cleavage, a succession of mitotic cell
divisions w/out growth between the divisions.
3. Cleavage leads to formation of multicellular stage called
blastula, in which animals take the form of a hollow ball.
4. Following blastula, gastrulation occurs and the layers of
embryotic tissues that will develop into adult body parts
are produced.
a. Coelom formation occurs during this stage.
5. The three layers, ectoderm, mesoderm, and endoderm, are
formed in the embryonic stage called, gastrula.
• Ectoderm: the germ layer covering the surface of the
embryo that gives rise to the outer covering of the
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animal, and in the case of bilateral animals, to the
central nervous system.
• Endoderm: the innermost germ layer, lines the
pouch that forms during gastrulation (the
archenteron) and gives rise to the lining of the
digestive tract, or cavity, and organs such as the
liver and lungs of vertebrates.
o Diploblastic refers to those animals w/ 2
germ layers (e.g., cnidarians).
• Mesoderm: in all bilaterally symmetrical animals; a
third germ layer that fills the space between the
ectoderm & endoderm.
o Triploblastic refers to those animals w/ 3
germ layers (e.g., bilateral animals).
▪ Mesoderm forms muscles & most
other organs between the digestive
tract & outer covering of the animal.
• Some diploblasts do have a third germ layer but it is
far less developed than the mesoderm of
triploblastic animals.
e) Development
▪ The life cycles of most animals include at least 1 larval stage.
• Larva: sexually immature form of an animal that is
morphologically distinct from the adult, usually eats
different food, & may even have a different habitat than the
adults.
• Animal larva eventually undergo metamorphosis, a
developmental transformation that turns the animal into a
juvenile that resembles an adult but is not yet sexually
mature.
▪ Vary widely morphologically, but the genes that control animal
development are similar across a broad range of taxa.
• Developmental/regulatory genes regulate the expression of
other genes & contain sets of DNA sequences called
homeoboxes.
32.3: Animals can be characterized by “body plans”
• Body plan: particular set of morphological & developmental traits, integrated
into the functional whole—the living animal.
• Symmetry, or lack there of, is the basic feature of animal bodies.
o Radial Symmetry: type of symmetry in which the body is lacking a left
side & a right side, & can be divided into mirror-imaged halves by a plane
through its central axis (e.g., sea anemones; shaped like a pie or barrel).
▪ In terms of movement, sessile animals live attached to a substrate
& planktonic animals drift or swim weakly (e.g., jelly fish).
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o Bilateral Symmetry: type of symmetry in which a central longitudinal
plane divides the body into 2 equal, but opposite halves (e.g., arthropods
and mammals).
▪ 2-sided symmetry
▪ Have 2 axes of orientation: a dorsal (top) side and a ventral
(bottom) side, a left and right side, and an anterior (front) end and
a posterior (back) end.
▪ Have sensory equipment concentrated at their anterior end,
including a central nervous system (brain) in the head.
▪ Unlike radial animals, bilateral animals typically move actively
from place to place. Their central nervous system enables them to
coordinate their complex movements.
o The symmetry of a particular animal generally fits its lifestyle.
• Body cavity: fluid- or air-filled space located between the digestive tract and the
outer body wall.
o The body cavity of triploblastic animals is called a coelom, which forms
from tissue derived from mesoderm; the inner and outer layers of tissue
connect and form structures that suspend the internal organs.
▪ Animals w/ a true coelom are called coelomates.
o Pseudocoelomates are triploblastic animals w/ a fully functional body
cavity that is formed from mesoderm and endoderm; such a cavity is
called a pseudocoelom.
o Acoelomates are triploblastic animals that lack a body cavity altogether.
o Functions of a body cavity:
▪ Its fluid cushions the suspended organs to prevent injury (e.g., in
soft bodied coelomates, such as earthworms, the coelom contains
noncompressible fluid that acts like a skeleton against which
muscles can work).
▪ Enables the internal organs to grow and move independently of
the outer body wall (e.g., if it weren’t for your coelom, every beat
of your heart or ripple of your intestine would warp your body’s
surface).
o Coelomates & pseudocoelomates have the same body plan and therefore
belong to the same grade (a group whose members share key biological
features).
o Protostome development is distinguished by the development of the
mouth from the blastopore; undergo either spiral or determinate cleavage.
▪ Spiral cleavage is a type of embryonic development in which the
planes of cell division that transform the zygote into a ball of cells
are diagonal to the vertical axis of the embryo; cells of each tier sit
in grooves between cells of adjacent tiers.
▪ Determinate cleavage is a type of embryonic development that
rigidly casts (“determines”) the fate of each embryotic cell very
early.
Document Summary
In terms of movement, sessile animals live attached to a substrate. & planktonic animals drift or swim weakly (e. g. , jelly fish). 2: body plan: particular set of morphological & developmental traits, integrated. In protostome development, as the archenteron forms, initially solid masses of mesoderm split and form the coelom. The blastopore and this 2nd opening become the 2 openings of the digestive tube: the mouth and the anus. In protostome development, the mouth general develops from the. In deuterostome development, the mouth is derived from the 2nd opening, and the blastopore usually forms the anus. 33. 1: sponges are basal animals that lack true tissues. Ballooning. : can catch insects by constructing webs of silk. built perfectly the 1st time, subphylum myriapoda (myriapods, millipedes & centipedes. Internal structure stores the sperm & it fertilizes multiple batches of eggs: bees, flies, etc. pollinate our crops & orchards. 16: extend appendages from their shell to strain food from water.
