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Vertebrate Zoology Study Guide Essay

I. Taxonomy

1. Reasons for Taxonomy
a. means of providing a systematic framework with which to work when studying the varied life forms inhabiting this earth
b. establishes order from chaos
c. Provides a system of nomenclature with which you label items (organisms)
d. necessary when imagining trying to gather information on an unfamiliar organism
e. Meant to provide a useful, convenient system using all evolutionary, adaptational, and anatomical aspects to classify

2. Carl Linnaeus: Swedish Scientist (1707-1778)
a. first person to truly systemize taxonomy
b. identified 236 different animal species, although classification based largely on morphology (based on structure)
c. lead to “inspiring” the study of classification

3. Factors used in Classification

a. system=hierarchial  b. must be able to discriminate among different types of organisms, must provide the criteria for the discriminations, must have the capacity for grouping smaller taxa/ taxon in larger, more inclusive taxa ( a hierarchial position (s) within a taxonomy) c. Artificial classification classes according to superficial resemblance (structure, color, habitat, etc. ) d. method used in zoology and biology is called natural classification e. Law of priority ( after a species has been described, defined, and illustrated) : any identification of a previously named species takes second priority, even if the new name if “more correct” f. rules/ factors based on Linnaeus’ Systema Naturae of 1758 ( *the factors and rules for nomenclature were established by the International Congress of Zoology in 1901 (the International Commission on Zoological Nomenclature)*

II. Evolutionary Advancements

1. Multicellular condition

a. cell number distinction increasingly important over the last few years b. Kingdom’s Protista and Monera mainly unicellular organisms c. Unicellular and multicellular organisms employ different methods to carry out life processes d. Example: the amoeba (unicellular) may regulate fluid levels by pinocytosis and water expulsion vesicles. A man must go through a much more complex process through numerous body structures to achieve the same ends. e. Cell number= quick indication of gross similarity/ difference

2. Coelem

a. the presence of a coelem is another animalian characteristic useful in taxonomy. b. Coelem=true body cavity, usually located in the area between the digestive tubes ( and other organs) and the outer wall of the animal c. Significance- permits relatively large size and complexity by creating greater surface area exposure, allowing diffusional and osmotic processes more chance to occur d. acoelemata (animals without a coelem)- jellyfish and flatworms e. Eucoelomata (animals with a coelem) thought of as “tube within a tube”; develops between somatic (outer) and visceral (inner) mesoderm lined with peritoneum f. Hemocoel (coelem where blood sloshes around, primitive circulatory system)-Mollusca, Arthropoda, Onychophora, etc. g. Pseudocoel (peritoneumless coelem)

h. Coelem of the earthworm broken into chambers/ septa.

3. Triptoblastic (can only occur in multicellular organism) a. Triptoblastic- having three germ layers (endoderm, ectoderm, mesoderm)- all other high level organisms b. Dipoblastic (endoderm, ectoderm)- coelentarata

4. Cephalization

a. Cephalization: when at the oral end, there exists a concentration of nervous tissues within a head b. cephalic, polar organism: has differentiation along longitudinal axis c. represents the most efficient means of reacting to most environments d. as complexity increases, animal tend to move unidirectionally e. visual area is vastly increased for erect or semierect terrestrial animals

5. Specialization of Organs and Organ Systems

a. Digestive tract: meant to process food and allow food to pass through where nutrients absorbed and waste secreted; porifera have no digestive cavity at all, enterozoa does have them b. Embryonic Development: used to create a new individual

Biogenetic Law: Ontogeny Recapitulates Phylogeny (evolutionary processes which take 1000’s of years to occur are compressed into a short period of time, in which an egg is fertilized and a new individual is created) c. Appendages: a body part protruding into the extraorganismal medium (Ex. Tentacles, legs, fins, wings, arms, etc.) d. Skeletal System: may represent position of organism in taxonomic sequence, or may be represented by lack of notochord (primitive vertebral column)

e. Sex: used to create offspring to prevent the extinction of the organism Dioecious organisms: unisexual, both sexes present but one individual has one set of gonads Monoecious organism/ hermaphroditic: have both sexual characteristics in each individual f. Larval Forms: may have ties to the body structure of organism in its adult form, which is why it could be considered so important

III. Difference between Homologous and Analagous structures

1. Homology

a. Homologous organs are fundamentally similar in structure b. always the same in embryological development having their origins in common ancestral types c. forelimbs of the frog, wings of a bird, and arms of a man serve to distinguish bearers from one another d. Homologous organs may have similar functions, but they may also not have similar functions; they simply must have embryological common ancestry

2. Analogy
a. analogous structures have similar functions b. the wings of a butterfly and the wings of a bird are both used to fly, but they are not homologous because they have neither the same fundamental structure nor the same embryonic origin.

IV. Key Characteristics of Phylum Chordata

1. Characteristics
a. notochord present in sometime in line
b. has dorsal nerve cord
c. blood flows in posterior direction in dorsal
d. gill clefts/ pharyngeal gills present in the embryos of all chordates
e. contains endoskeletons
f. contains a post-anal tail
g. significant advancement: paired limbs
h. contains a ventral heart, and a hepatic portal system
i. contains Cyclostomes (lampreys, eels, and hagfish), cartilaginous fish, Osteothys (bony fish), birds, and mammals j. bilateral symmetry, and is tripoblastic

V. Evolution of Lamprey

1. Life cycle of Lamprey
a. Spawns in cool, clear streams, where they construct nests out of small stones which is collected by the mouth. b. Semelparity- this occurs when the adult organism dies after spawning. c. starts as a larvae called ammocoetes

d. Ammocoetes are filter feeders in small burrows in the stream bottom mud.This stage lasts for about ten years. e. Metamorphosis- a dramatic change in which the larvae changes to suit the next stage. f. If non-parasite then it can now spawn, if not then it is now at a stage where it can capture a host . It feed on flesh, blood and body fluids. There is rapid growth during this period. g. Soon feeding stops, they become sexually mature, and migrate to spawning areas.

2. Type of Nutrition of Lamprey

a. Ectoparasitism: eats like a parasite
b. latches onto a victim
c. Sucks the blood out of victim

3. External Anatomy Structures and Functions
a. Terminology:
Anterior/cranial/rostral/cephalic/cephalid-towards the front or the head Posterior/caudal/caudad-towards the rear or tail
Dorsal-towards the top of the body near the spinal cord
Ventra-Towards the belly or underside of the body
Lateral-towards the sides of the body
Media-towards the middle of the body or midline
Proxima-near the base of a structure

b. Elongated body with no appendages typically divided into three regions c. head- extends forward from the bronchial (gill)
-buccal funnel lacks jaws, but is fringed with sensory papillae, these papillae can also work as a air tight suction seal. -lined with keratinized horny teeth and not homologous to the true teeth of other vertebrates -The protrusible tongue is attached to the ventral side of the mouth which is at the center of the funnel. The tongue has lingual teeth. This is used to scrape a hole in the host. -7 pairs of external gill slits leads to respiratory gill slits, which lead to respir. gill pouches -eye movement is very limited

-median nostril for olfaction (smell)
-Pineal cornea is the small patch of skin behind the nostril. This protects the pineal gland. The pineal gland regulates the endocrine system and the bio clock of the lamprey.
d. trunk-Main body between gill and vent

– The muscles of the lamprey right underneath the thin layer of skin are called myomeres.
– Two dorsal fins, anterior dorsal fin-anterior to the cloaca – posterior dorsal fin: taller
– Cloaca is the opening that expels the wastes which Is received by the anus. It recieves urinary wastes via Urogenital papilla.
– Next to the cloaca is the urogenital aperture, this is where gametes are expelled
– Males have bigger u. papilla while female have small anal fins e. caudal-extends backwards from the vent

4. Buccal Cavity Structures and Functions
a. Buccal Papillae: around the edges of the mouth of the lamprey, the buccal papillae are used as suction to allow the lamprey to hold onto its prey b. Keratinized Horny Teeth: the horny teeth are used to grip the prey c. Lingual Teeth: the lingual teeth have teeth on it, which are used to drill d. Buccal Glands: Buccal glands secrete digestive enzymes

e. Supra Oral: above, top of the mouth
f. Infra Oral: below, bottom of mouth

5. Structure and Function of CNS

-nostril of lamprey opens into olfactory sac, which then leads to hypophyseal canal to a blind chamber, the hypophyseal sac. -Hypophyseal sac=dorsal to the pharynx and esophagus, extends under the brain and notochord, terminating near the second gill slit – folds of tissue lining olfactory sac covered with sensory epithelia for chemoreception – Information from receptors in olfactory sac directly transmitted to brain, constantly aware of chemoenvironment – eyes seen in the first cross section of the head

-Focus by adjusting distance between lens and retina to achieve the correct focal length -Brain of lamprey divided into 3 different parts: hindbrain (rhomobencephalon), midbrain (mesencephalon), and forebrain (prosencephalon) -has 10 crainal nerves

-has only 2 semicircular canals for orientation and balance – originating at posterior end of brain running dorsal to the notochord: spinal cord -nerves exit at each body segment until they are completely separated into dorsal and ventral nerve roots -dorsal to the spinal column=fat column(may be conspicuous and dark in some cases)

6. Structure and functions of Digestive System

a. No true stomach; the esophagus grades directly into the intestine; both digestion and absorption occurs in the intestine. b. Anticoagulant, cytolytic, and proteolytic enzymes start digestion and are secreted by the buccal glands. c. These glands empty on to the underside of the tongue and works on the host tissues directly.

d. In the larval stage the folding in the intestine is called the typhosole, some folds are spirally layed out so some call it the spiral valve e. The liver is a large, single-lobed, triangular shaped structure located just below the intestine, Is a characteristically green color f. the bile duct connects the liver to the intestine and either emerges at meta. or disappears in other. g. There is no discrete pancreas. All enzymes are secreted by localized portions of the body such as the intestine, buccal cavity or the esophagus.

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