Zoology Test 1 PDF

Theory of Evolution - Charles Darwin hypothesized an evolutionary model based on natural selection - “The March of Progress” - depicts the evolution and advancement of humans from ape-like organisms, created by Rudolph Zallinger Lamarckian Evolution - Traits acquired during an organis...

Theory of Evolution - Charles Darwin hypothesized an evolutionary model based on natural selection - “The March of Progress” - depicts the evolution and advancement of humans from ape-like organisms, created by Rudolph Zallinger Lamarckian Evolution - Traits acquired during an organism’s lifetime due to use or environmental influence are inherited by offspring Jean-Baptiste de Lamarck - One of the first scientists to propose a theory of evolution in his 1809 book, “Philosophie Zoologique” - The book argued three issues of evolutionary change: 1. Fact - evolutionary change is real and observable 2. Course - life arose spontaneously and evolved towards complexity (change arose as a result of need) 3. Mechanism - evolutionary changes are inheritable Lamarck’s Hypothesis 1. Inheritance of acquired characteristics - Traits developed or “acquired” during an organism’s lifetime due to environmental pressures could be passed down to its offspring 2. Use and disuse - Frequently used traits become stronger and more developed, while unused traits weaken and eventually disappear 3. Adaptation through need - Organisms change in response to their needs, meaning their physical form could directly respond to their environment Darwinian Evolution - Inherited genetic variation and natural selection drive changes in a population, with beneficial traits becoming more common over generations Charles Robert Darwin - Naturalist of the HMS Beagle’s voyage (1831–1836) - Wrote the 1859 book “On the Origin of Species” - Proposed the conditions for and mechanism of evolutionary change - Descent with modification and natural selection Alfred Russell Wallace - Darwin’s contemporary, collected biological specimens from the Amazon to the Malay Archipelago - Independently and coincidentally arrived at the same motion of natural selection as Darwin Darwin’s Hypothesis 1. Descent with modification - Organisms have a single origin of life (common ancestry) - Lineages with different forms arose via splitting from existing lineages - Forms are different from, but not necessarily more complex, or others 2. Natural selection - Survival of the fittest - Variations exist in populations - “Useful” variations for survival will be “preserved” and passed onto offspring - Variational theory of change - the frequency of a variant increases from one generation to the next Components of Darwinian Evolution - Evolution - characteristics of organisms change over time - Gradualism - differences between species evolved in small steps through time  - Common descent - all or a set of species diverged from a common ancestor - Populational change - change in population of variants in a population - Natural selection - certain features that make organisms more “fit” to their environment = higher survival Modern Evolutionary Synthesis - After Darwin - Adaptive evolution - caused by natural selection acting on (Mandelian) genetic variation Microevolution - Evolution within species 1. Mutation 2. Gene flow 3. Natural selection 4. Genetic drift Macroevolution - Evolution above species 1. Evolutionary novelties 2. Dispersal and vicariance events 3. Speciation 4. Other processes Linnaean Classification Scheme - Domain - Bacteria, Archaea, Eukarya - Kingdom - Animalia, Plantae, Fungi, Protista - Phylum - sharing general body plans and characteristics - Class - more specific shared features - Subclass - a subdivision within a class, refining classification further - Order - similar characteristics - Family - organisms that are closely related - Genus - very similar and closely related - Species - basic unit of classification, representing a single type of organism - Subspecies - variations within a species that occur in different geographic locations or conditions Examples:  - Humans - eukarya, animalia, chordata, mammalia, primates, hominidae, homo, sapiens - Domestic dog - eukarya, animalia, chordata, mammalia, carnivora, canidae, canis, canis lupus, canis lupus familiaris Phylogenetic Tree - aka Evolutionary tree - Shows the evolutionary history of species based on genetic or morphological data, with branch lengths often representing time or the degree/magnitude of change - More complex and detailed compared to the cladogram Cladogram - Depicts the relationship between different organisms based on the presence or absence of shared characteristics - Focuses on the order of the branching, disregarding time or genetic information Cladistic Concepts - Monophyletic - Contains all descendants of a single common ancestor - The preferred way of grouping organisms in modern taxonomy - ex. Class Mammalia - Paraphyletic - Leaves out one or more descendants of the common ancestor - Ex. Reptiles (excludes birds) - Polyphyletic - Formed based on superficial similarities, but does not include the most recent common ancestor - Ex. Bats and birds (flight)  NOTE: All animals are multicellular, but not all have tissues Binomial Nomenclature - Genus species (Author, year) - The universal system for naming organisms, ensuring that every species has a unique and recognized name - Italicized when typed and underlined when written - ex. Homo sapiens (Linnaeus, 1758) Phylum Porifera - aka Sponges - The most basal animal group - Sessile filter feeders that are bound to the seabed, characterized by bearing pores on their body - Larvae are pelagic and planktonic - Mostly marine (8600+ sp.) but can be freshwater (150+ sp.) Poriferan Body Plan Movement Planktonic as larvae and sessile as adults Organ complexity Cellular grade (no true organs) Cells Multicellular, with no true tissues Body symmetry Asymmetrical or radial Germ layers None (non-embryonic development)  Developmental pattern None Cleavage None Body cavities None (no true coelom) Other characteristics - Digestion: intracellular through choanocytes engulfing food particles, before being digested within amoebocytes - Respiration: diffusion across cell membranes as cells absorb oxygen through water flowing into the body - Excretion: diffusion, with ammonia diffusing out of cells and carried away by the current - Asexual reproduction: gemmulation (top), budding (bottom), and fragmentation - Sexual reproduction: external, with gametes being fertilized in the water and planktonic larvae (may be flagellated) - Typically dioecious (hermaphroditic) Types of Sponges 1. Encrusting - Grows as thin, spreading, layers that adhere closely to surfaces like rocks, corals, and other hard substrates (irregularly shaped) - Uses these hard surfaces for protection from potential predators and harsh water currents - Often found in high-energy environments with stronger water currents such as rocky intertidal zones and coral reefs - ex. Many sponges in class Demospongiae 2. Free-Standing - Grows in various three-dimensional shapes, including barrel, tube, vase, or branching forms - Independent from substrates and often taller, allowing for enhanced filtration and more robust structural support Pinacoderm - The outermost, protective layer of the sponge, consisting of a thin, flat layer of cells called pinacocytes - Helps regulate water flow by controlling the size of the ostia - Water enters the spongocoel through the many ostia, and exits through one single osculum Mesohyl - a gelatinous, protein-rich extracellular matrix that fills the space between the outer pinacoderm and the inner layers (ex. choanocyte layer) - Acts as a connective tissue that houses various cells and skeletal components, providing structural support and helping with internal transport of waste and nutrients - Spongin - collagen-based protein fibers that provide structural support and gives the sponge elasticity and resilience - Spicules - Structural elements secreted by sclerocytes that provide support and defense, acting as a kind of internal skeleton for the sponge - Calcareous - Made up of calcium carbonate, making it more fragile and less durable in acidic or deep-sea environments - Siliceous - Made up of silica and can act as optic fibers, which allows light to be transmitted Cells - Pinacocytes - Flat, thin protective cells that help maintain the sponge’s shape - Minor movement and contraction of the body, regulating pores and controlling the flow of water - Archaeocytes - aka Amoebocytes - Can differentiate/specialize into other cell types, making them totipotent cells - Moves freely in the mesohyl, and is involved in digestion, nutrient transport, immune response, and repair/regeneration - Collencytes - stationary and star-shaped, responsible for secreting collagen, forming and supporting the mesohyl, giving the sponge elasticity and flexibility - Lophocytes - highly mobile, responsible for secreting collagen and depositing collagen fibers as they move to produce the sponge’s structural framework  - Spongocytes - produces spongin, a fibrous protein that forms part of the skeleton; especially common in sponges that lack a rigid mineral skeleton (ex. class Demospongiae) - Sclerocytes - secretes spicules, forming the sponge’s rigid support structure for its shape and defensive purposes - Choanocytes - Collared, flagellum-bearing cells that resemble choanoflagellates (unicellular eukaryotes) - Found in the internal canals and chambers - Responsible for creating water currents through the sponge to capture food particles (suspension-feeding) Canal Systems - Asconoid - The simplest, most primitive, and least efficient at filtering large volumes of water - Usually smaller in size and often in more shallow waters - Choanocyte configuration: lines the spongocoel; only able to collect food from water adjacent spongocoel walls - Water flow: ostia > spongocoel > osculum - ex. Class Calcispongiae - Syconoid - More efficient because of the increased surface area for filtering - Similar in appearance to asconoid but with a thicker and more complex body wall, and canals created by the inward folding of the spongocoel - Choanocyte configuration: lines the canals, with none in the spongocoel itself - Water flow: ostia > incurrent canals > radial canals > spongocoel > osculum  - ex. Scypha - ex. Class Calcispongiae or Hexactinellida - Leuconoid - The most common, complex, and efficient - Usually in larger sponges, including those in deep-sea environments - Has flagellated chambers which increase the surface area for water filtering - Choanocyte configuration: lining the chambers filled with incurrent canals - Water Flow: ostia > incurrent canals > flagellated chambers > excurrent canals > osculum - ex. All sponge classes Spongocoel - The central cavity of the sponge where water collects after passing through the sponge’s canal systems - Not a true coelom - Asconoid - it is a simple, large cavity, with a straightforward water flow pathway - Syconoid - surrounded by a more complex canal system, where water passes through radial canals before reaching it - Leuconoid - either reduced or absent because od a complex network of flagellated chambers Suspension-Feeding 1. Water enters from the canals of pore cells (dermal ostia) in pinacoderm 2. Water enters the spongocoel 3. Collars of choanocyte trap food particles a. Food vacuoles envelope trapped food (phagocytosis)  b. Protein molecules taken in (pinocytosis) 4. Water exits the sponge via the large osculum — Class Calcispongiae - aka Calcarea - Small (2m in diameter - Velum - absent  - Manubrium - the central, tubular structure hanging from the underside of the bell with 4 oral arms, connecting the mouth to the gastrovascular cavity Class Cubozoa - Voracious predators that are known for their potent venom, complex eyes, and more active swimming style - Structure: usually small, with a cube- or box-like shape with tentacles hanging from each corner - Reproduction: A complex life cycle that includes a polyp stage (small and inconspicuous) and a dominant medusa stage - Can either be dioecious or hermaphroditic depending on the species - ex. Box jellyfish, irkunadji jellyfish Medusa - Pedalium - flat, paddle-like structures at the base of each tentacle, aiding in propelling the medusa through the water - Velarium - forms an inward fold that forms at the opening of the bell, aiding in contraction to help in directing water flow for enhanced swimming - Manubrium - relatively short and may have a distinct shape - Radial pouch - extensions of the gastrovascular cavity that extend out into the bell, playing a role in digestion and nutrient distribution - Gonad - reproductive organs within the radial pouches that produce gametes Class Staurozoa - aka Stalked jellyfish - Solitary polyps known for having a stalk and for not having a medusa stage (entirely sessile) - Structure: a polyp that is typically attached to a substrate by an adhesive disc, with a bell-like structure at the top and tentacles radiating from it - Reproduction: either sexual or asexual, with non-swimming planula (larvae) - ex. Common stalked jellyfish Class Anthozoa - Known for also not having a medusa stage, along with their flowerlike appearance - Structure: tubular bodies and a mouth surrounded by tentacles (either solitary or colonial) - Reproduction: either sexual through releasing gametes into the water or asexual through budding or fragmentation - ex. Sea anemones, stony coral Subclass Hexacorallia - Order Scleractinia  - aka Hard or stony corals - Typically having a colonial structure, where individual polyps are interconnected and share a common calcareous skeleton - Its polyps have six tentacles arranged in multiples of six - Hexamerous septa - divides the gastrovascular cavity that contribute to structural integrity and better digestion - Primarily found in tropical and subtropical marine environments, often forming coral reefs - Order Actiniaria - aka Sea anemones - Often have mutualistic relationships with other species (ex. clownfish), protecting it from predators as it gains food through the fish’s waste - Pedial disc - a flat, disc-shaped region at the base, allowing for attachment and detachment from substrates - Sphincters - circular muscles that constrict or relax to control the opening of certain body parts, and can aid in asexual reproduction - Found in various marine environments from shallow waters to deeper regions, often associated with substrates like rocks, shells, and coral reefs Subclass Ceriantipatharia - Order Ceriantharia - aka Tube anemone  - Builds tubes of mucus and secretions that they retract into for protection - Has long, slender tentacles that extend out of the tube to catch plankton - Found in shallow and deep waters, typically buried in soft sediments such as sand or mud - Order Antipatharia - aka Black and whip corals - Colonial organisms with dark, hard, and thorny skeletons - Living colonies, despite the name, actually have a range of colors - Commonly found in deep-sea environments or areas with strong currents Subclass Octocorallia - aka Octocorals - Includes corals with eight-fold symmetry: eight pinnate (feather-like tentacles) and eight unpaired septa - Its internal skeletons are made of a flexible protein called gorgonin or calcium carbonate in some cases - Found in shallow to deep waters, often forming colonies on coral reefs and rocky outcrops — Reef-building groups - Organisms (ex. corals, algae) that actively contribute to the formation and growth of coral reefs - Colonies with lasting carbonate structures - Primarily made up of hard or stony corals (ex. order Scleractinia, subclass Octocorallia) - Endosymbiotic zooxanthellae - Unicellular dinoflagellates that contribute to the production of coral mucus - Increases the energy and growth of corals, all while gaining protection and nutrients from it Reefs - Apo Reef Natural Park - the 2nd largest reef system worldwide - Danajon Bank - the only double reef in the Philippines Phylum Ctenophora - Aka Comb jellies - Voracious and active predators that are of abnormal shapes for jellyfish - Known for their often transparent and bioluminescent bodies - Found in marine environments, from shallow, coastal waters to the deep sea Ctenophoran Body Plan Movement Planktonic with the use of ciliary combs Organ complexity Cell-tissue grade (no true organs) Cells Multicellular, with true tissues  Body symmetry Biradial, with eight rows or ciliary combs Germ layers Diploblastic Developmental pattern None Cleavage Holoblastic Body cavities Gastrovascular cavity (no true coelom) Other characteristics - Digestion: extracellular in the pharynx and intracellular, with waste being expelled through anal pores - Respiration: diffusion, with gas exchange occurring directly through the body surface - Excretion: diffusion, with ammonia being expelled into the water - Sexual reproduction: external, with gametes being fertilized in the water and developing into cydippid larvae - Typically dioecious Lophotrochozoa - Animals with a lophophore (a ciliated feeding structure) or trochophore larvae - Protostome development pattern; either spiral or mosaic - Larvae are very small and translucent - ex. Platyhelminths, annelids, molluscs, bryozoans, brachiopods