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Biol 114 Final Exam Review Notes
- Course
- Biology 114
- Institution
- State University Of New York - Binghamton
Final exam review notes for Biol 114. *Essential Study Material!!
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Biol 114 Fall 2020Lecture week 8 (10/12-10/16)
Animal Diversity
I. Introduction.
II. What is an animal?
A. Basic animal characteristics.
1. Heterotrophic lifestyle, deriving nutrition by consuming other life forms. **consumers**
2. Flexible cell membranes, (like plant cells ,but unlike them in that plant cells are
surrounded by a cell wall made rigid by cellulose) and associated Extracellular Matrix
(ECM)-->osteoblasts are bone cells that have bone as its ECM.
3. Glycogen, a carbohydrate energy storage product (compared to starch in plants).
4. Neuromuscular tissue, Associated with movement. The vast majority of animals show
locomotion, at least in their larval stages (in Chordates, only the adult sea squirts are attached
to their substrate).
● Germ layer: a collection of similarly produced cells. (analogous to a meristem in a plant)
B. Protist ancestors of Animalia
1. Choanoflagellate protists are the closest living relative of the animals.
2. The Phylum Porifera is the most ancient animal phylum with living representatives.
There is a similarity between the feeding cell members of the choanoflagellate and
choanocyte cells of the sponges. Choanocyte cells are cells with an attached cylinder of
microfibrils within which a flagellum resides.
3. “Micro-feeders” These “flagellated collar cells” not only show a phylogenetic connection
between protists and animals, but support the belief that these specialized cells evolved when
only the smallest suspended organisms were available as food (e.g., bacteria and early
protists). No animals, other than sponges, are able to capture such small food items.
III. Fundamental traits used to define major animal groups
A. Number of germ layers (layers of similar dividing cells (analogous to plant meristematic cells).
Each germ layer produces a characteristic subset of structures/organs in the adult animal.
1. No primary germ layer. Although different looking cells come together and function as a
multicellular organism, the cells remain totipotent--they can become anything (e.g., sponges).
2. Diploblastic. Two major germ layers form, from which different structures develop. 1)
The ectoderm – the outer layer and 2) the endoderm – the inner layer. The ectoderm gives
rise to the skin and nervous system structures, and the endoderm gives rise to the lining of the
digestive tract (e.g., Cnidarians-jellyfish, coral polyps, sea anemones).
3. Triploblastic. Three major germ layers. 1) The ectoderm and 2) endoderm form the
same types of structures as in 2 above. 3) The mesoderm (meso-meaning “middle”) gives
rise to the muscles, bones, and most organ systems (e.g., all other animals).
B. Body symmetry.
How many planes can you put through an organism to produce a mirror image of themselves. With higher
levels of organization, the body becomes more symmetrical and cephalized (development of a “head”),
where sense organs and nerve tissues are concentrated at the leading edge of movement. There are three
main types of symmetry. Leading edge...leading with head to gather information from the environment.
1. Asymmetry. The animal cannot be subdivided into equal, but opposite, halves (e.g.,
sponge).
, 2. Radial Symmetry. Condition in which many planes will divide an organism into equal,
but opposite halves so long as the plane goes through the center of the animal. These animals
have a circular body with equally effective action/response in all directions (e.g., jellyfish,
starfish).
3. Bilateral Symmetry. Condition in which only one plane will subdivide the animal into
equal halves (e.g., mammals, reptiles, birds, humans, etc).
C. Body Cavity--triploblastic organisms
Space that exists between the digestive system and the outer body wall. Among those animals with a
mesoderm, the body cavity separates internal organs from the body wall, allowing greater
maneuverability.
1. Acoelomate. No body cavity exists (e.g., flatworms).
2. Pseudocoelomate. Animal has a body cavity without a mesodermal lining of organs,
allowing better diffusion of substances inside the organism and better maneuverability.
However, a certain amount of rubbing between the organs and body wall occurs in these
animals (e.g., nematodes).
3. Eucoelomate. Animal has a body cavity and internal organs covered with a membrane
derived from mesoderm. This form provides the best protection from rubbing and foreign
antigens entering the coelom from a wound. This condition is found in most higher
organisms.--have to find a way to get fluids into the organs….have to go through the
mesodermal lining. -evolved at the same time of pseudocoelomates but they only made up a
small portion
D. Embryology
Within the triploblastic organisms, the fate of the embryonic blastopore (first infolding) helps to
distinguish phyla. Blastosphere has an infolding of the endodermal cells...Those that have the blastopore
resulting in a mouth are considered Protostomes, and those where it becomes the anus are called
Deuterostomes.
IV. Classification of phyla
A. Asymmetric animals without germ layers.
1. Phylum PORIFERA (sponges) –
The sponges represent a dead-end phylum (that is they did not give rise to any other
existing phyla) are benthic, sessile filter feeders with variable body sizes and complex
water canals throughout their bodies. Sponges had very few competitors in early seas
(see micro-feeding above), but had the need for defenses against predators, using both
chemical and physical (sharp spicules) defenses. The commercial sponge trade has been
replaced by the invention of synthetic sponges.
B. The radiates – diploblastic animals with radial symmetry.
1. Phylum: CNIDARIA (animals containing cnidocyte cells – e.g. coral, anemones, and
jellyfish) –
These animals evolved when macroscopic protists were abundant, well after sponges
evolved. These animals were sessile or slow-moving hunters that used attached
paralyzing harpoons (nematocysts in cnidocyte cells) to capture prey or for defense.
Sessile forms (e.g., coral) supplement energy with a mutualistic algae. Most cnidarians
have a multipurpose, blind, gastrovascular cavity, extending to most of the body tissues
for nutrient delivery.
,C. Lophotrochozoan protostomes – Triploblastic animals with bilateral symmetry, a blastopore
becoming a mouth, and showing growth by incremental additions to the body (without having to
shed to grow).
1. Phylum: PLATYHELMINTHES (flatworms)
This phylum includes free-living flatworms and parasitic flukes and tapeworms. The
most primitive groups include bilateral symmetry, cephalization, and typical
tube-within-a-tube design. The flat body maximizes surface area for diffusion of gasses
(they have no respiratory system). This group represents the first bottom-dwelling, flat,
slow-moving scavengers, also including well-developed chemoreceptors for localizing
food.
2. Phylum: ANNELIDA (segmented worms)
This group likely evolved from a free-living flatworm and includes earthworms,
predatory marine worms, and leeches. Marine worms were the first annelids (and
majority of existing annelids today). Later annelids radiated into freshwater and onto
land. Annelids have a hydrostatic (liquid-inflated) skeleton and gripping setae, both of
which assist in burrowing through substrate. Annelids have repetition of body parts
along the body axis (segmentation) allowing independence of body parts. Earthworms
are important in cycling nutrients in ecosystems.
3. Phylum: MOLLUSCA (chitons, snails, clams, squid, octopus and others)
The mollusks are the second largest phylum (first is Arthropoda) and extremely diverse,
and are likely to have evolved from an annelid ancestor. Adaptive radiation is due to
several innovations, including a mantle, protective shell, muscular foot, and a scraping
radula, all allowing the early mollusks to feed on suspended and attached algae near
shore. Only snails moved onto land. Many of the species are used for food. Some, like
the Zebra Mussel, are problematic. Mantel: the shell. Muscular foot: helps organism
move and filter feed within their environment.
D. Ecdysozoan protostomes – Triploblastic animals with bilateral symmetry, a blastopore
becoming a mouth, and showing growth via repeated shedding of the outer body exoskeleton
(ecdysis).
1. Phylum: NEMATODA (nematodes or roundworms)
Members of this phylum occur in most habitats, including other organisms, and likely
evolved from a flatworm ancestor. The number of individual nematodes is much greater
than the number of all other animals combined. Nematodes are tolerant of a variety of
extreme conditions, including drought (>39 years), freezing and boiling, O2depletion, and
low pH. Primary among their adaptations is the evolution of a cuticle (protective,
dehydration-resistant body covering that is shed to permit growth. Nematodes play an
active role in nutrient cycling. They are the most abundant multicellular organism that
feeds on bacteria and fungi in decaying plants and animals. Nematodes are also a
concern to animals, causing diseases like Trichinosis and Elephantiasis.
2. Phylum: ARTHROPODA (insects, crustaceans (crabs, lobster, shrimp, etc.), and
spiders (mites, ticks, scorpions, etc.))
The arthropods dominate our landscape in abundance and numbers of species (80% of all
known animal species – 70%of all animal species are beetles). Arthropods evolved from
an annelid ancestor (arthropids have segmentally arranged appendages/bodies). The
, chitinous external skeleton (exoskeleton) was the innovation that met all the criteria for
moving out of the water and onto land. The mollusks had heavy shells. The marine
worms were segmented for flexibility, but movement with parapodia didn’t allow for
speed on land. The arthropod’s exoskeleton has strength, is economical, and allows for
speed of movement. Later arthropods evolved a tracheae system (small breathing tubes
to the inner body parts) and a compound eye (for spotting food from a distance, rather
than just bumping into it.
E. Deuterostome Phyla – Deuterostomata = “second mouth”; the mouth is the second opening to
develop during embryonic growth, the anus being the first. In the Protostomes (= “first mouth”),
the mouth is the first opening to develop, the anus being the second. Early embryological
differences like these reveal the early divergence of two fundamentally different evolutionary
lines of animal phyla, the protostomes and deuterostomes. Animals in the deuterostome phyla
have bilateral symmetry, triploblastic germ layers, and eucoelomate body cavities.
1. Phylum: ECHINODERMATA (starfish (sea stars), sea urchins, and sea cucumbers)
Echinoderms represent the closest non-chordate relative to the chordates, based on
genetic information and larval type. However, a common ancestor between echinoderms
and the chordates is unknown. Overall, echinoderms are slow-moving, omni-directional,
heterotrophs, with spines for protection. They have arms with gripping suction cups for
locomotion and predation.
2. Phylum: CHORDATA (all with a notochord or more)
a. This phylum is comprised of progressively more mobile, more rigid-bodied
heterotrophs. In addition to an increase in cephalization, there are 4 key chordate
characteristics.
i. Notochord – fibrous support rod along the back appearing at least during early
development (replaced by a vertebral column in the adult in later evolved
chordates.
ii. Pharyngeal gill slits – initially used in filtering food suspended in water, but
later just for respiration.
iii. Dorsal hollow nerve cord – a single dorsal nerve for rapid sensory processing.
iv. Post-anal tail – a portion of a tail extends posteriorly past the anus (effective
for locomotion in early evolution).
b. There are 3 chordate subphyla: Urochordata, Cephalochordata, and Vertebrata.
Within the Vertebrata there are 6 major classes:
i. Chondrichthyes – cartilaginous fishes (sharks and rays) – first chordates with
jaws.
ii. Osteichthyes – bony fishes – includes all feeding modes (mostly carnivorous,
but also algivores, suspension feeders, and scavengers.
iii. Amphibia – frogs, toads, and salamanders – first chordates to invade land, but
have to stay close to water.
iv. Reptilia – Lizards, snakes, turtles, and crocodiles – dry, keratinized skin
allowed reptiles to be fully terrestrial. Became the ruling terrestrial vertebrates in
the Mesozoic Era (Age of Reptiles).
v. Aves – birds – first chordates adapted for flight
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