Zoology

The scientific study of the diversity of animal life.

• Zoon - Animal
• Ology - the study of

Study its 600 million year history

Evolution

1) Reconstruct phylogeny (tree of life) of all animals on the planet and locate the origin of multicellularity, acoelom, radial cleavage, vertabrae and homeothermy.

2) Understand evolutionary processes that generate and maintain diversity.

Multicellularity

A body of knowledge gained from studying the natural world. It is tested gainst the natural world but does not use natural selection. It's conclustions are not absolute, new discoveries can revise previous conclussions. It is falsifiable, nothing is ever proven, just not falsified.

To understand the natural world, learn to protect the natural world and develop skills for learning.

All that you can see around you.

• Observation
• Question
• Hypothesis
• Empirical Test
• Conclussions
• Publication

• Observed that smallpox was deadly, survivors are immune, milkmaids did not get smallpox but did get cowpox.
• Hypothesis - cowpox make you immune to smallpox.
• Prediction - If you're exposed to cowpox you will be immune to smallpox.
• Results - People never got smallpox.
• Conclussion - Failed to falisify that cowpox makes you immune to smallpox.

Failure to falsify repeated testing of various hypotheses all leading to the same conclussion.

Theory - guess or speculation

Scientific theory - principle that is tested many times and explains many different phenomena

Law is an observation that has been repeated many times such as the Law of Gravity, it does not explain an observation.

Theory explain how or why something happens in nature. Theory explains the most, lows hypothesis and facts.

Germ Theory - Germs cause disease.

Things are made of tiny atoms.

Genes on chromosomes determine heredity.

All living things are made of cells.

Darwin found exidence of Evolution in the results of artificial selection, or the selective breeding of plants and animals.

Fossil record shows perpetual change, it reveals that organisms have evolved in a historical sequence.

Charles Wallcot discovered the Burgess Shale in 1913. The fossils are about 570 million years old and reside in the Burgess Shale in the Rockies of British Columbia.

The comparison of body structures in different species.

The similarity in the characteristics that result from a common ancestor.

A feature that has different functions but is structurally similar due to a common ancestory.

The same features but not because of a common ancestor.

The comparison of early stages of development amount different organisms. Many vertibraes have common ebryonic structures.

The comparison of DNA and amino acid sequeces between different organisms that reveal evolutionary relationships.

The geographic distribution of species.

They resembled species of SOuth American mainland. The island were similar but distant. Some island were volcanic and some continental. They had different species but the same climate.

Insects deveolped a resistance to pesticide.

A multicellular animal.

Various grades of organization.

Callular grade - cells demonstrate division of labor but are not strongly associated together. (no tissue)

Tissue grade - Cells aggregate together to form a tissue to performa common function.

Organ grade - Several types of tissue grades working together (digestive tract)

Organ system grade - organs working together to form systems.

Spherical - any plane through the center divides body into half.

Radial - tend to be circles - can be divided in half by more than two planes - Jellyfish

Bilateral - Can only be divided in half on the sagittal plane to get equal halves.

• Sagittal - head to toe
• Transverse - forms front and back
• Frontal - forms top and bottom
• Anterior - Towards the head
• Posterior - towards butt
• Ventral - belly
• Dorsal - back

They are much better fitted for forward movement through their environment.

Cephalazation.

The differentiation of the head end of an organism, this is a mechanism during the development that makes head and tailbone during embryogenisis. You can't have one without the other, must have both growth and development.

Zygote, which divides into many smaller cells.

Spiral - layers of cells do NOT stack but are attanged in currows - also known as mosaic clevage.

Radial - Layers of cells stacked on top of each other - also known as regulative clevage

Invertibrates have spiral and vertibrates have radial.

They form a zygote with 23 chromosomes from each, the zygote forms a blastula, the blastula then invaginates (folds in) to form gastula, the gastrula then forms the gastrocoel which forms the digestive tract.

From the gastrula.

• Endoderm is the inner tissue.
• Ectoderm is the outer tissue.

• Two - way (incomplete) Mouth but no anus.
• One - way (complete) Mouth to anus.

Middle layer of tissue.

A tube may form called a coelome.

Pseudocoelomates - coelom forms but not completely surrounding the mesoderm.

Accoelomate - no coelom forms - the mesoderm fills the blastoceol

Eucoelomate - Completely surrounded by mesoderm "tube within a tube" body plan

Sponges, they have no true tissue, they are the only animals without tissue.

Jellyfish, they only develope two tissue types, endo and ecto. They also have radial symetry

Three tissue types, acoelomate, pseudocoelamate and Eucoelomates.

• Enterocoelome forms from the digestive tract.
• Schizocoelome forms between the gut and ectoderm.

Both are eucoelomates.

Radial clevage and regulative embryos, can have twins.

Have spiral clevage, cannot have twins, and have mosaic embryos.

The opening to the digestive trace.

The study of tissues.

Epithelial - Forms skin, covers and lines organs, derivded from the ectoder and endoderm.

Connective - Holds tissues and organ systems together, derivded from the mesoderm, tendons, bone, blood, ligaments.

Muscle - Allows for movement, also derived from mesoderm.

Nervous - Allows for coordination, derived from ectoderm.

Choanoflagellates.

They are protists (single celled) some form colonies and all are filter feeders.

Mesozoa - single clade of worm parasites that infects marine invertabrates.

Parazoa - Besides animals - includes sponges.

Eumetazoa - All other animals.

All animals are mullticellular hetertrophs.

Multicellular, body have spores (ostia) no organs or true tissues, no nervous system, adults are sesile and attach to substratum. The skeletons can be made of calcareous spicules, siliceous spicules, or spongin. All are aquatic, most are marine.

• Calcarea - calcium
• Hexactinellida - Silicon
• Demospongiae - Fake, Sponge bob

Adult forms grow on rocks, shells, corals, or some other substrate.

They use Choanocytes to bring in food and oxygen.

They have a collar of microvilli that traps food. They beat their tail (flagella) to move the water and trap the food in the collar.

They can be fiborous and rigid. The rigid portion is calcareous and/or siliceous and the fiberous portion is made of collagen (spongin)

• Outer layer compose of pinacocytes.
• Inner nonlayer mesoglea contains a variety of specialized cells (Mesohyl and Mesenchyme)
• Collar cells(choanocytes) which capture food from water flowing through canals.

• Asexual by budding or demmuales.
• Sexual by sperm and egg.

Choanocytes - line canals and chambers, traps food particles and phagocytize them, pass on digested food to archeocytes, larger particles passed to prosopyl.

Archeocyes - Ameboid cells that move about the mesohyl, can phagocytaize food at pinacoderm or recieve from choanocytes.

Pinacocytes - form the external layer, thin flat epithealeal cells, t shaped body, regulate water intake, located in the mesohyl

Asconoid, Syconoid, Leuconoid.

This is the simplist form. Has ostium, porocyte, spongocoel, osculum, limited number of canals which limits food intake, usually narrow spongocoel.

• They are the most complex. Very effective at absorbing food.
• Ostium to the incurrent canal to the flagellated chamber to the excurrent canal to the spongocoel and out the osculum. The water usually goes through more than one flagellated chamber.

Has no choanocytes in the spongocoel, choanocytes are located in the radial canal.

Ostia to the incurrent canal to prosopyl to radial canal to apopyl to spongocoel out the osculum.

Sexual, monoecious, they are both male and female, sperm and egg are derived from the choanocytes, they have ciliated larvae which swim to new locations. Some are viviparous, the larvae grows inside them some oviporous, fertilization takes place outside - Grantea is an example of VIVIPAROUS

Asexual - budding, fragmentation, gemule formation. These usually survive harsh conditions, the archaocyes differenciate into other cell types.

• Budding - grows off parent
• Fragmentation - Produce lots of clones
• Gemule - mainly freshwater - Filled with archaeocytes

Small, vase shaped, can be asconoid, syconoid or leuconoid. Spicules consist of calcium carbonate, they are straight or 3 - 4 rays.

Deep sea forms, vase or funnel shaped, spicules consist of siliceous (usually 6 or more rays) can be Syconoid or Leuconoid. Example is the Venus Flower Basket

• 95% of sponge species, mostly marine except family Spongillidae, spicules consist of siliceous (spongin)
• ALL LEUCONOIDS!

Contains more than 9,000 species, takes its name from Cnidocytes (nematocysts), stinging organell in Cnidocytes, very old group (700 million years)

• Polyp (benthic type) - rests on the floor
• Medusa (pelagic type) floats

Asexual and sexual

Endoerm (gastrodermis) and Ectoderm (epidermis)

A two-way (incomplete) gut, they have both extracellular and intracellular digestion. They have nerve cells that form a nerve net. They have sense organs and a primitive muscular system that is not derived from the mesoderm.

Radial

In shallow water, they are mostly marine. They "serve" food for some marine fish and moouscs. They live symbiotically with other organisms. They form coral reefs.

They have adaptations that allow them to float or swim, they have a thick jelly like mesoglea

They are attached to the bottom of the ocean by a pedal disc, reproduce by budding, fission, pedal lacerations (tissue forms polyps) All are clones of the parent. Non-colony forming polyps can move by their basal disc.

Medusa types are poor swimmers, they usually float, Portugeuse man of war moves by wind. Some move by contracting.

Zygote developes into planula, planula settles forms a polyp, which may produce other polyps, eventually forms a medusa type. Medusa type reproduces sexually or through gametes. Most but not all take both forms.

Mouth takes in food, have extracellular and intracellular.

• The body wall is diploblastic, it consists of two tissue layers. The ectodermal which gives rise to the epidermis and Endodermal which gives rise to gastrodermis.
• The mesoglea is NOT a true tissue layer because it is not composed of cells!

The gastrodermis is large, columnar, lined with epithelial cells. Nutritive muscular cells contains myofibrills (muscle fibers) Food is brought in by the beating of cilia, contains food vacuoles. Some species contain photosynthetic protists (green hydra) Gland cells release enzymes for digestion.

Contains epithelimuscular cells (for covering and contrations), interstitial cells (stem cells), gland cells (secrete mucus), cnidocytes (stinging cells)

Cnidocytes contain cnidae which are covered by operculum, there are various types of cnidae. Use poison injection, entangle pray, have an adhesive substance and are reabsorbed and replaced when they are discharged.

They contain flagellum, the nerve cells form connections with sensory cells and other nerve cells, cnidocytes and epitheliomuscular cells which form neuromuscular "tissue" (not organ system) Nerve cells are aranged in a "nerve net" - there is NO central nervous system

Some stay attached and form colonies, these have ONE gastrovascular cavity, many different specialized "zooids" (little animals) for things like food, protection, reproduction.

• Fresh water & marine, cnidocyte only in epidermis
• medusa present with a muscular velum
• mesoglea without ameboid cells
• asexual reproduction by budding
• sexual via gametes produced by epidermis & released into water.

Freshwater, polyp solitary, no medusa stage, typically found on underside of leaves & lillies in cool clean water. attached to surface with pedal disc, mouth surrounded by tenticles that wound their pray, wounded organism produce glutithyone, triggers feeding response. Both asexual and sexual reproduction.

Colony former, both polyp and medusa type, asexual and sexual, plolyp buds and do not detach from colony, medusa also released by budding, release sperm and egg for sexual reproduction

Bell of medusa folds in, forms velum, mouth at end of manubrium leads to the radial canal that connects with velum and finally to tentacles. True Jellyfish DO NOT HAVE VELUM!!

• Portuguese Man-of-War
• Colony former, medusa and polyp, has a float carries it with the wind, contains gas filled sac, individuals bud from it and hang suspended in water, specialized polyps

• Tentacles up to 70 meters in length, Cnidocytes present in gastrodermis & epidermis Thick mesoglea contains Ameboid cells. Gametes produced by gastrodermis
• ALL MARINE

Bell margine is scalloped & contains Phonplium (sense organ) manubrium is drawn out into four oral arms, four gastric pouches connect to radial canals that branch to ring canal, sexes are separete - fertilization is internal, sperm carried into gastric pouches in females

Madusa dominant and cuboid, tentacles arise at four corners from blade like pendlium, ALL MARINE, strong swimmiers, pray mostly on fish, stings of some may kill humans in minutes, such as Sea Wasp

No medusa stage, solitary or colony forming, some produce protective skeletons, gastrovascular cavity subdivided into 8 or more mesentaries (speta), Cnidocytes on mesentaires, Mesoglea contains ameboid cells, ALL MARINE, protective skeleton made of calcium carbonate, polyps retract when not feeding, Two main types are Zoantharian (hard) and Octocorallian (soft)

Hard typically has 8 tentacles, form coral reef, calcareous spicules & gorgonin protein

Photosythenthetic dinoflaglletes (brown), live in corals, provide nutrients for coral by photosythesis, mutualism