what to know for test

protostomes

A major grouping of animals that develop the mouth from the blastopore in the embryonic stage, which includes phyla such as arthropods and mollusks.

deuterostomes

A major group of animals that develop the anus from the blastopore in the embryonic stage, including phyla such as chordates and echinoderms.

phylum porifera

-sponges

-dont move

-porous body

-cells for intracellular digestion

-most don’t have symmetry or some radial

-no coelom

-invertebrate so endoskeleton

-asequal reproduction and sexual

coelum

A body cavity lined by mesoderm, forming a central space for organs and tissues in complex animals.

cephalisation

The evolutionary trend toward the concentration of sensory and nervous tissue at the anterior end of an organism, leading to the formation of a head region.

cnidaria

-one gut opening mouth or anus

-polyp or medusa jellyfish corals

-radial symmetry

-no coelum

-inverterbrate

Platyhelminthes

-flat worms

-aquatic

-could be parasitic

-one gut opening

-bilateral symmetry

-cephalisation

-no coelom

-protostomes

-invertebrate

Nematoda

-hook worms and pin worms

-aquatic and terrestrial

-bilateral

-cephalisation

-no true coelom

-protostomes

-both mouth and anus

-invertebrate

Mollusca

micromullusks to giant squid, snails, clams, octopus, aquatic some terrestrial.

-many have a shell

-radula:tongue like structures

-muscular foot

-bilateral

-cephalisation

-coelom

-protostomes

-invertrebrate

annelid

-earthworms, leeches, tubeworms

-can be aquatic and terrestrial

-segmented (repeated body parts)

-little hair like structures-help move or swim

-bilateral

-cephilsation

-coelom

-protostomes

-invertrebrate

arthropoda

-ant, insects, spiders, crustaceous

-aquatic/terrestrial

-fly (some)

-exoskeleton

-bilateral

-cephalisation

-coelom

-protosomtomes

-invertebrate

echinodermata

-sea stars, sea urchins

-aquatic saltwater

-most larvae are bilateral but as adults are radial

-regrenarte portions of structure

-no cephalisation

-coelom

-invertebrate

chordata

-fish amphibians(tetrapods) birds mammals

-notochord turns to vertebrate

-dorsal nerve cord, pharyngeal slits, postnatal tail and thyroid gland

-aquatic

-terretsrial

-some can fly

-bilateral

-cephalisation

-true coelom

-deuterostomes

germ layers

Ectoderm

• Origin: The outermost germ layer.

• Derivatives: Primarily forms structures that interact with the external environment.

  • Nervous System: Brain, spinal cord, nerves.

  • Epidermis of Skin: Hair, nails, sweat glands, sebaceous glands.

  • Sensory Organs: Eyes, inner ear.

  • Enamel of Teeth.

  • Lining of Anus and Nostrils.

2. Mesoderm

• Origin: The middle germ layer, located between the ectoderm and endoderm.

• Derivatives: Forms most of the muscular, circulatory, skeletal, and excretory systems.

  • Muscular System: Smooth muscle, cardiac muscle, skeletal muscle.

  • Skeletal System: Bones, cartilage.

  • Circulatory System: Heart, blood vessels, blood cells.

  • Excretory System: Kidneys, bladder.

  • Reproductive System: Gonads and associated ducts.

  • Connective Tissues: Dermis of skin, tendons, ligaments, fascia.

  • Lining of Body Cavities (peritoneum, pleura, pericardium).

3. Endoderm

• Origin: The innermost germ layer.

• Derivatives: Primarily forms the lining of the digestive and respiratory systems, and associated glands.

  • Lining of the Digestive Tract: Esophagus, stomach, intestines.

  • Lining of the Respiratory Tract: Larynx, trachea, bronchi, lungs.

  • Glands associated with the Digestive System: Liver, pancreas.

  • Thyroid and Parathyroid Glands.

  • Thymus.

  • Lining of the Urinary Bladder.

diploblastic vs triploblastic

• Diploblastic Animals: Animals like Cnidarians (jellyfish, corals) and Ctenophores (comb jellies) have only two germ layers: the ectoderm and endoderm. They lack a true mesoderm, though they may have a non-cellular layer called mesoglea between the two layers.

• Triploblastic Animals: Most other multicellular animals, including flatworms, segmented worms, mollusks, arthropods, echinoderms, and chordates, possess all three germ layers: ectoderm, mesoderm, and endoderm. The presence of a mesoderm allows for the development of more complex organ systems and muscle

heart chambers

Heart chambers are specialized compartments within the heart that pump blood. The number and complexity of heart chambers vary across different animal groups, reflecting their circulatory needs:

1. Fish (e.g., bony fish):

   • Two chambers: One atrium and one ventricle.

   • Circulation: Single circulatory system. Deoxygenated blood enters the atrium, moves to the ventricle, is pumped to the gills for oxygenation, and then travels directly to the rest of the body before returning to the heart.

2. Amphibians (e.g., frogs):

   • Three chambers: Two atria (right and left) and one ventricle.

   • Circulation: Double circulatory system, but with mixing of oxygenated and deoxygenated blood in the single ventricle. The right atrium receives deoxygenated blood from the body, and the left atrium receives oxygenated blood from the lungs/skin. The ventricle pumps blood to both the lungs/skin and the body.

3. Reptiles (most, e.g., lizards, snakes, turtles):

   • Three chambers (with a partial septum): Two atria and one ventricle with an incomplete septum. This partial division reduces the mixing of oxygenated and deoxygenated blood compared to amphibians.

   • Circulation: Double circulatory system. Deoxygenated blood from the body enters the right atrium, oxygenated blood from the lungs enters the left atrium. Both flow into the partially divided ventricle, which then pumps blood to the lungs and the body.

4. Crocodilians, Birds, and Mammals:

   • Four chambers: Two atria (right and left) and two ventricles (right and left), completely separated by a septum.

   • Circulation: Complete double circulatory system. This highly efficient system completely separates oxygenated and deoxygenated blood, allowing for high metabolic rates.

     • Right Atrium: Receives deoxygenated blood from the body.

     • Right Ventricle: Pumps deoxygenated blood to the lungs.

     • Left Atrium: Receives oxygenated blood from the lungs.

     • Left Ventricle: Pumps oxygenated blood to the entire body (systemic circuit). The left ventricle has thicker muscular walls as it needs to generate higher pressure to pump blood to all parts of the body.

carnivore digestive tracks

1. Carnivore Digestive Tracts

Carnivores (e.g., cats, wolves) consume diets rich in protein and fat, which are relatively easy to digest and have high energy density.

• Diet: Primarily meat, which is readily broken down by gastric acids and enzymes.

• Digestive Tract Length: Generally short relative to body size. This is because meat is highly digestible

• Stomach: Large and acidic (low pH, typically pH 1-2). This strong acidity is crucial for denaturing proteins, activating protein-digesting enzymes (like pepsin), and killing bacteria present in raw meat. It is a single-chambered, simple stomach.

• Small Intestine: Relatively short, designed for efficient and rapid absorption of amino acids, fatty acids, and vitamins.

• Large Intestine: Short and simple, primarily involved in water absorption and waste compaction. The cecum (a blind-ended pouch at the junction of the small and large intestines) is often very small or vestigial, as it has no significant role in fermentation.

• Microbial Fermentation: Minimal to none, as their diet does not contain significant amounts of complex carbohydrates like cellulose.

herbivore digetsive tracks

2. Herbivore Digestive Tracts

Herbivores (e.g., cows, horses, rabbits) consume plant material, which is rich in cellulose and other complex carbohydrates. These are difficult to digest and have a lower nutrient density, requiring specialized adaptations for microbial fermentation.

• Diet: Primarily plant matter (cellulose, hemicellulose), which requires microbial assistance to break down.

• Digestive Tract Length: Generally long and complex relative to body size. This extended length provides sufficient time and surface area for microbial fermentation and nutrient absorption.

• Stomach/Fermentation Chambers: Highly specialized.

  • Ruminants (Foregut Fermenters): (e.g., cattle, sheep, goats)

    • Possess a four-chambered stomach: Rumen, Reticulum, Omasum, and Abomasum (true stomach).

    • The rumen and reticulum are large fermentation vats where symbiotic bacteria, protozoa, and fungi break down cellulose into volatile fatty acids (VFAs), which are absorbed as the primary energy source. This process also synthesizes B vitamins and essential amino acids.

    • Food is regurgitated as cud and re-chewed to further break down plant fibers (rumination).

    • The omasum absorbs water and remaining VFAs.

    • The abomasum functions as the 'true' glandular stomach, secreting acid and digestive enzymes.

  • Non-Ruminant Hindgut Fermenters: (e.g., horses, rabbits, elephants, kangaroos)

    • Have a simple, single-chambered stomach, similar to carnivores.

    • Microbial fermentation occurs in the hindgut, primarily in an enlarged cecum and/or a specialized colon.

    • This strategy allows for faster processing of large volumes of food but is less efficient than ruminant digestion because nutrients produced by microbes in the hindgut (e.g., microbial protein, vitamins) cannot always be absorbed by the host animal (as they occur after the main absorption sites in the small intestine).

    • Some hindgut fermenters, like rabbits, practice cecotrophy (ingesting soft, nutrient-rich fecal pellets produced by the cecum) to re-digest and absorb microbial products.

• Small Intestine: Typically long to maximize nutrient absorption.

• Large Intestine: Often very long and complex (especially in non-ruminant hindgut fermenters), featuring an enlarged cecum and/or colon for extensive microbial fermentation and water absorption.

• Microbial Fermentation: Essential for breaking down cellulose, providing the host with energy (VFAs) and sometimes other nutrients.

fish circulative system

Heart Structure

The fish heart is typically a two-chambered organ, though anatomically, it comprises four serially arranged components, often referred to as 'chambers' due to their role in blood flow:

• Sinus Venosus: A thin-walled sac that collects deoxygenated blood from the main veins of the body (e.g., hepatic vein, common cardinal veins) before it enters the atrium.

• Atrium (Auricle): A thin-walled, muscular receiving chamber that collects blood from the sinus venosus and pumps it into the ventricle.

• Ventricle: The thick-walled, most muscular pumping chamber of the heart. It generates the high pressure required to propel blood through the gill capillaries and then the systemic circulation.

• Conus Arteriosus (in cartilaginous fish) / Bulbus Arteriosus (in bony fish): An elastic, muscular chamber located after the ventricle. It helps dampen the pulsatile flow from the ventricle, maintaining a more continuous pressure to the gills and preventing damage to the delicate gill capillaries.

2. Blood Flow Pathway (Single Circulation)

In a single circulatory system, blood passes through the heart only once during each complete circuit of the body. The pathway is as follows:

1. Deoxygenated blood from the entire body (including the head, trunk, and fins) is collected by systemic veins and enters the sinus venosus.

2. From the sinus venosus, blood flows into the atrium.

3. The atrium contracts, pushing the deoxygenated blood into the robust ventricle.

4. The ventricle contracts forcefully, pumping the deoxygenated blood anteriorly into the conus arteriosus or bulbus arteriosus.

5. Blood then proceeds from the bulbus/conus arteriosus to the ventral aorta, which branches into afferent branchial arteries leading to the gill capillaries.

6. At the gill capillaries, gas exchange occurs: oxygen (O2O2) is absorbed from the water, and carbon dioxide (CO2CO2) is released. The blood becomes oxygenated here.

7. The now oxygenated blood collects in the efferent branchial arteries, which merge to form the dorsal aorta. This vessel then distributes oxygenated blood to all tissues and organs of the body (systemic circuit).

8. As oxygen is delivered to the tissues and carbon dioxide is picked up, the blood becomes deoxygenated and returns to the heart via the systemic veins, completing the circuit.

monophyletic, paraphyletic and polyphyletic group

1. Monophyletic Group (Clade):

• A group that includes a common ancestor and all of its descendants.

• Represents a complete branch on the tree of life.

• Example: All mammals, all birds.

1. Paraphyletic Group:

   • A group that includes a common ancestor but not all of its descendants.

   • Occurs when one or more descendant lineages are excluded from the group.

   • Example: Reptiles (excluding birds, even though birds evolved from reptiles), fish (excluding tetrapods).

2. Polyphyletic Group:

   • A group composed of organisms from different evolutionary lineages that do not share a recent common ancestor.

   • The common ancestor of all members of a polyphyletic group is not included in the group.

   • Often arises from convergent evolution, where unrelated organisms independently evolve similar traits.

   • Example: Flying vertebrates (bats, birds, pterosaurs - they evolved flight independently and don't share a recent common flying ancestor).

homologous vs analogous

Homologous structures are anatomical features in different species that share a common ancestry, despite possibly serving different functions.

Analogous structures, on the other hand, are features in different species that serve similar functions but do not share a common evolutionary origin.

convergent vs divergent

Homologous structures are anatomical or molecular features found in different species that share a common ancestral origin, even if they have evolved to serve different functions in the descendants.

Analogous structures are features in different species that perform similar functions but do not share a recent common evolutionary origin. Their similarity is due to similar environmental pressures or lifestyles rather than shared ancestry.