Animal Taxonomy and Systematics PDF

ANIMAL TAXONOMY AND SYSTEMATICS domain Bacteria, and distinct from Archaea. Systematic - study of the diversity of organisms and their relationships 3. Phylum - a rank that further di...

ANIMAL TAXONOMY AND SYSTEMATICS domain Bacteria, and distinct from Archaea. Systematic - study of the diversity of organisms and their relationships 3. Phylum - a rank that further divides kingdoms into more specific groups based on Taxonomy - science of classifying and naming general body plans and major structural organisms based on their characteristics. differences. Taxonomic Ranks: Example in Animalia: 1. Domain - highest and broadest rank in the o Chordata: Animals with a biological classification. notochord (includes Divides all life into three broad groups: vertebrates). Bacteria: Prokaryotic, unicellular o Arthropoda: Animals with organisms. jointed legs and an exoskeleton (insects, Archaea: Prokaryotic, unicellular crustaceans). organisms distinct from bacteria in their biochemistry and genetics. 4. Class – within each phylum, organisms are further divided into classes, which are smaller Eukarya: Organisms with eukaryotic and more specific groups. cells, including animals, plants, fungi, and protists. Example in Chordata: 2. Kingdom - subdivision of a domain, o Mammalia: Animals that are grouping organisms that share broad warm-blooded, have hair or similarities in cell structure and organization. fur, and produce milk. In the Eukarya domain, the main o Aves: Birds, characterized by kingdoms include: feathers and flight. o Animalia: Multicellular 5. Order - each class is subdivided into animals. orders, grouping organisms based on more specific similarities. o Plantae: Multicellular plants. Example in Mammalia: o Fungi: Includes mushrooms, molds, and yeasts. o Primates: Includes humans, apes, monkeys, and lemurs. o Protista: Mostly unicellular organisms, like algae and o Carnivora: Mammals that protozoa. primarily consume meat (e.g., lions, wolves). o Monera: An outdated kingdom that included all prokaryotes. 6. Family - orders are divided into families, which group organisms that share even more o Eubacteria: The true bacteria, specific characteristics and are often visibly now classified under the similar. Example in Primates:  o Hominidae: The family that Species name: This is not includes great apes and capitalized but is also italicized humans. (e.g., sapiens). 7. Genus - groups of species that are closely Example: Homo sapiens related and very similar, usually sharing a (humans), Panthera leo (lion). recent common ancestor. 2. Phylogenetic System - based on Example: evolutionary relationships. o Homo: The genus that Carolus Linnaeus – created the basic includes humans and their biological taxonomy, binomial classification closest extinct relatives. system. o Panthera: Includes large cats Carl Woese - developed the three-domain like lions (Panthera leo), tigers system of classification. (Panthera tigris), and leopards (Panthera pardus). PHYLUM: PORIFERA 8. Species Phylum Porifera, or sponges, are notable for Most specific rank in taxonomy, their porous bodies and lack of true tissues defining a group of individuals that can and organs (they have no digestive system interbreed and produce fertile and nervous system). offspring. Body Systems: Example: o Ostia - small pores or openings found o Homo sapiens (Humans) on the surface of sponges through o Panthera leo (Lion) which water enters the sponge's body. o Spongocoel – central cavity o The skeletal support structure of Classification Systems sponges is composed of silica, 1. Linnaean System – hierarchical (a calcium carbonate, and spongin. hierarchical system organizes o Osculum - large opening at the top of organisms into groups based on shared the sponge through which water and characteristics). waste products exit. o Prospyle - term given to the entry - Binomial nomenclature (is a two- hole/channel/pore leading into the part system for naming species). area of choanocytes. Each species is given a name Body symmetry: consisting of two parts: o Most sponges exhibit an Genus name: This is capitalized asymmetrical symmetry, but some and italicized (e.g., Homo). exhibit a radial symmetry. o Mesohyl - a gelatinous matrix that is filled in the space between the  external outermost layer called PHYLUM: CNIDARIA pinacoderm and the internal layer Phylum Cnidaria is a group of aquatic, called choanoderm. It provides mostly marine organisms that includes well- structural support to the sponge. known species such as jellyfish, sea Specialized Cells: anemones, corals, and hydra. o Porocyte – cells controlling current. Body Symmetry: They create closable valves in order to Radial symmetry: Cnidarians have a body control or limit the passage of current. plan that can be divided into similar halves o Sclerocyte – cells that makes spicules along any plane through their central axis. or sharp tiny spines that deter predators. Body Forms: o Choanocytes – primary cells responsible for generating water Cnidarians exhibit two main body forms: currents and capturing food in 1. Polyp: Sessile (non-moving) form, sponges. typically cylindrical, with the mouth o Amoebocyte – cells that and tentacles facing upward (e.g., sea allow conduction signals for luring of anemones, corals, hydra). prey 2. Medusa: Free-swimming form, bell- Canal Systems: shaped, with the mouth and tentacles o Leuconoid canals - canal system that facing downward (e.g., jellyfish). do not have a central spongocoel. Some Cnidarians, like jellyfish, They possess flagellated choanocyte alternate between polyp and chambers. medusa forms during their life cycle. o Asconoid canals - simplest type among canal systems. Diploblastic Organization: Reproduction: Cnidarians have two germ layers: o Sponges reproduce asexually through o Ectoderm: Forms the outer layer budding, fragmentation, or the of the body (epidermis). production of gemmules. o Endoderm: Forms the inner lining o Sponges reproduce sexually by of the gastrovascular cavity fertilization of eggs and sperm. (gastrodermis). Water circulation and food consumption: o These layers are separated by a o Water circulation of sponges: gelatinous, non-cellular layer Water enters the sponge through small called the mesoglea, jelly-like pores called ostia, moves through the substances that contribute to the spongocoel, and is expelled through structure and buoyancy. the larger opening called the osculum. Gastrovascular Cavity - serves as the This flow is generated by the beating of digestive chamber where extracellular choanocyte flagella. digestion occurs, circulation of nutrients, and waste removal.  o There is only one opening (the eventually settles and transforms into mouth), which serves as both the a polyp. entrance for food and the exit for waste. Life Cycle of Cnidarians Hypostome - it is a conical or dome-shaped elevation located at the oral end of cnidaria, The typical life cycle of Cnidarians (e.g., right above the mouth. jellyfish) alternates between the polyp and medusa forms. Tentacle - specialized structures that extend from the body and play a vital role in feeding, Sexual Reproduction: The medusa produces defense, and locomotion gametes (eggs and sperm) that fertilize in the water to form a zygote. Simple Nervous System: Planula Larva: The fertilized zygote develops o The ganglion neurons of cnidarians into a free-swimming, ciliated planula larva, form a decentralized nerve net, a which eventually settles onto a substrate. simple and diffuse nervous system without a central brain, that enables Polyp Stage: The planula metamorphoses basic sensory processing and stimuli into a sessile polyp. In some species, the polyp responses. may reproduce asexually by budding to form o Cnidocytes are specialized cells more polyps. unique to Cnidarians that contain nematocysts—stinging organelles Medusa Formation: In many Cnidarians, the used for capturing prey and defense. polyp eventually undergoes a process called When triggered, the nematocyst ejects strobilation, where it produces medusae a harpoon-like structure that can inject asexually. These medusae mature into the toxins into the target adult form. o They also have statocysts, sensory Classification of Species structures that help them maintain balance. Scyphozoa - is commonly referred to as the "true jellyfish. Reproduction: Anthozoa - a class within the phylum Cnidaria Cnidarians reproduce both asexually and that includes well-known marine organisms sexually: such as sea anemones, corals, and sea o Asexual reproduction occurs mainly pens. in the polyp stage, through processes like budding, where new individuals grow from the parent organism. PHYLUM PLATYHELMINTHES o Sexual reproduction usually involves Phylum Platyhelminthes, or flatworms, the medusa stage, where gametes are comprises a diverse group of invertebrate released into the water for fertilization. animals characterized by their flat, soft- The resulting zygote develops into a bodied morphology planula, a free-swimming larva that Digestive system:  Predation: Many flatworms are Platyhelminthes lack specialized predators that feed on other small respiratory and circulatory systems. animals, such as insects, Respiration: Flatworms respire crustaceans, and other invertebrates. through simple diffusion across their They typically capture their prey using thin body surface. As they have a specialized structures, such as flattened body shape with a high muscular pharynx or proboscis, surface area-to-volume ratio, oxygen which they use to engulf or pierce their can easily diffuse across their body prey. surface and reach their cells, while Scavenging: Some flatworms are carbon dioxide diffuses out. scavengers that feed on dead or Circulation: Flatworms lack a well- decaying organic matter. developed circulatory system. Parasitism: A significant number of Instead, they rely on diffusion and flatworms are parasites that obtain simple fluid-filled spaces to nutrients and energy from their host transport nutrients, gases, and waste organisms. products within their body. Symbiosis: Some flatworms form Excretion: Flatworms excrete waste mutualistic relationships with other products, such as ammonia, through organisms, where both partners their body surface by diffusion. benefit. For example, some flatworms Triploblastic: live in the digestive tracts of animals, such as cows and horses, and help Ectoderm: The outermost layer, which digest cellulose in plant material, develops into the skin, nervous while obtaining nutrients in return. system, and certain sense organs. Reproductive system: Platyhelminthes Mesoderm: The middle layer, which exhibit diverse reproductive strategies, gives rise to muscles and the excretory including sexual (fertilization) and asexual system reproduction (budding). Endoderm: The innermost layer, which forms the lining of the digestive Nervous system: Platyhelminthes possess a tract. simple nervous system that typically includes a pair of ganglia and a network of nerve fibers. PHYLUM NEMATODA Sense organs: can include simple Phylum Nematoda, commonly known as eyespots or ocelli that can detect roundworms, is a large and diverse group of changes in light intensity, allowing invertebrate animals characterized by their flatworms to navigate their elongated, cylindrical bodies that taper at surroundings. both ends. Nerve networks: flatworms possess a ladder-like nervous system, consisting Body Structure: of a network of nerve cells or neurons Shape: Flatworms exhibit a flattened, Respiration and Excretion: bilaterally symmetrical body.  Tissues: They possess three germ amphids and phasmids, which are layers (triploblastic): ectoderm, used for detecting chemical and mesoderm, and endoderm. physical stimuli in the environment. Having triploblastic, bilateral, Flatworms have a simple nervous vermiform, unsegmented, system that includes a pair of cerebral pseudocoelomate body ganglia (often referred to as a "brain") and two ventral nerve cords with Body Cavity: lateral branches. Flatworms are acoelomates, meaning Muscle System: they lack a true body cavity. The space between the tissues is filled with a Nematodes lack circular muscles parenchyma, a type of tissue derived They have three muscle layers: from mesoderm. circular, longitudinal, and diagonal, A typical nematode body have a allowing for various movements, simple body plan, with a cylindrical including gliding and swimming. shape and tapered ends. The longitudinal muscles are the Their body is covered by a tough and principal means of locomotion flexible exoskeleton called a cuticle. Reproductive System: Three primary layers make up Most flatworms are hermaphroditic, the cuticle: cortex, matrix layer, and possessing both male and female basal layer. reproductive organs. They can Digestive System: reproduce sexually or asexually, with some capable of regeneration. Complete digestive tract; mouth usually surrounded by lips bearing Classification: sense organs. Class Secernentea (Phasmidea): The mouth has either three or six lips has phasmid (glandular or sensory arranged around the mouth opening, structures) in the tail region which often have a series of teeth on their inner edges. amphids are poorly developed in the anterior end They possess a gastrovascular cavity with a single opening that serves as Excretory system is present both mouth and anus. Class Adenophorea Aphasmidia): Nervous System: absent Phasmids They lack circulatory and respiratory systems and have a simple nervous most-free-living, but some parasitic system. species occur. The anterior end of the body contains sensory structures, such as the PHYLUM ANNELIDA allowing for coordinated movement and flexibility. Phylum Annelida, known as segmented worms, is a diverse group of invertebrate Reproductive System: animals characterized by their segmented Annelids can be dioecious (having bodies. separate male and female individuals) Body Structure: or hermaphroditic (possessing both male and female reproductive organs). Segmentation: Annelids have a Many species reproduce sexually, segmented body plan, with each while some can reproduce asexually segment (or somite) containing a through fragmentation. similar set of structures. This segmentation allows for greater flexibility and specialization of body PHYLUM ARTHROPODA parts. Phylum Arthropoda is the largest phylum as it Shape: They have elongated, encompasses almost one million named cylindrical bodies that are often species. It is also known as a vast array of tapered at both ends. invertebrate animals known for their jointed Body Cavity: appendages, segmented bodies, and exoskeletons made of chitin. Annelids are coelomates, meaning they possess a true coelom (body Body Structure: cavity) lined with mesoderm, which Segmentation: Arthropods have a allows for the development of complex segmented body plan, typically organs and systems. divided into three main regions: head, Digestive System: thorax, and abdomen. Some groups may have additional tagmata (body They have a complete digestive tract sections). that includes a mouth, pharynx, esophagus, crop, gizzard, and Exoskeleton: They possess a hard intestine. The digestive system is exoskeleton made of chitin and highly specialized for their feeding calcium carbonate, which provides habits. protection and support. This exoskeleton must be molted (ecdysis) Nervous System: as the organism grows. Annelids have a well-developed Tagmatization is a characteristic nervous system, including a dorsal feature of arthropods, such as insects, nerve cord and a ventral nerve cord, crustaceans, and spiders. It refers to with ganglia in each segment acting as the division of the body into distinct local control centers. segments or regions called tagmata, Muscle System: which are specialized for different functions. Their muscular system consists of circular and longitudinal muscles, Jointed Appendages: encompassing a wide range of species such as snails, clams, squids, and octopuses. Highly developed sense organs: (1) Mollusks are characterized by their soft Compound eyes; (2) Antennae: bodies, which are often protected by a hard sensory appendage; (3) Olfactory shell. Receptors; (4) Gustatory Receptors, and (5) Statocysts. Body Structure: Arthropods have paired jointed Body Plan: Mollusks typically have a appendages, which can be modified three-part body plan consisting of: for various functions, including o Head-foot: The anterior locomotion, feeding, and region containing the head reproduction. (with sensory organs and Body Cavity: mouth) and the muscular foot used for locomotion. Arthropods are coelomates, possessing a hemocoel (a fluid-filled o Visceral mass: The central body cavity) that serves as a region containing most hydrostatic skeleton. internal organs. Respiratory System: o Mantle: A significant tissue layer that covers the visceral Respiration occurs through various mass and secretes the shell (if structures, including gills (in aquatic present). arthropods), tracheae (in insects), and book lungs (in some arachnids). Shell: Many mollusks possess a hard calcareous shell made of calcium Nervous System: carbonate, although some groups, Arthropods have a well-developed like octopuses, have either reduced nervous system with a dorsal brain shells or none at all. and a ventral nerve cord, along with Body Cavity: specialized sensory organs (e.g., compound eyes, antennae). Mollusks are coelomates, possessing a true coelom, but it is reduced to a Reproductive System: small cavity around the heart and Most arthropods have separate sexes reproductive organs. The main body (dioecious), and reproduction may cavity is a hemocoel, which is part of involve complex mating rituals. Many the open circulatory system. arthropods undergo metamorphosis, Circulatory System: with distinct larval and adult stages. Most mollusks have an open circulatory system, where blood flows PHYLUM MOLLUSCA freely in the hemocoel. However, cephalopods (like squids and Phylum Mollusca is one of the largest and octopuses) possess a closed most diverse groups of invertebrate animals,  circulatory system, allowing for more structures, such as spines and efficient oxygen transport. tubercles. Respiratory System: Skin: The skin is often covered with spines or tubercles and may have Mollusks typically respire through gills various textures, including soft and (ctenidia) in aquatic species or flexible in sea cucumbers. through a lung-like structure (Pallial Cavity) in terrestrial gastropods. Water Vascular System: Nervous System: A unique hydraulic system used for locomotion, feeding, and respiration. Mollusks exhibit a wide range of It consists of a network of canals filled nervous system complexity, from with seawater, including the simple nerve nets in bivalves to highly madreporite (a porous plate that developed brains in cephalopods. regulates water intake), radial canals, Reproductive System: and tube feet. Mollusks can be dioecious (separate Tube feet operate through hydraulic sexes) or hermaphroditic (having both pressure, allowing echinoderms to male and female reproductive organs). move, cling to surfaces, and capture Many species have complex life prey. cycles, including larval stages like Digestive System: trochophore and veliger. Echinoderms generally have a complete digestive system, although PHYLUM ECHINODERMATA the structure varies widely among different classes. Many have a Phylum Echinodermata consists of marine specialized feeding apparatus (e.g., invertebrates known for their unique radial the Aristotle's lantern in sea urchins). symmetry and water vascular system. Echinoderms include familiar species such as Nervous System: starfish (sea stars), sea urchins, sand dollars, They have a decentralized nervous and sea cucumbers. They are exclusively system without a true brain. Instead, marine animals they possess a nerve ring around the Body Structure: mouth and radial nerves extending into each arm or body section. Radial Symmetry: Adult echinoderms typically exhibit pentamerous radial Reproductive System: symmetry (five-part symmetry), Most echinoderms are dioecious although some species can show (having separate sexes) and reproduce variations. sexually through external fertilization. Endoskeleton: They possess an Some species can also reproduce internal skeleton made of calcareous asexually through regeneration. plates (ossicles) that can form distinct PHYLUM CHORDATA Phylum Chordata is a diverse group of 4. Endostyle or Thyroid Gland: animals that share certain key features at o Recently, the endostyle was some stage of their development. This phylum recognized as a includes vertebrates (animals with shared chordate character. backbones) as well as some invertebrate groups, such as tunicates and lancelets. o The endostyle or its derivative, the thyroid gland, is found in Chordates share four defining features at all chordates. some point in their life cycle: o Located in the pharyngeal 1. Notochord: floor, it secretes mucus that o A flexible, rod-like structure traps small food particles in that provides support. In many the pharyngeal cavity. vertebrates, the notochord is 5. Post-anal Tail: replaced by the vertebral column (spine) during o An extension of the body that development. extends beyond the anus. It may be present during 2. Dorsal Hollow Nerve Cord: embryonic development in o A tube-like structure that some chordates and is usually develops into the central modified in many species. nervous system (brain and spinal cord) in vertebrates. It runs along the back (dorsal side) of the organism. 3. Pharyngeal Slits: o These are openings in the pharyngeal region (throat area) that may develop into gill structures in aquatic animals or evolve into various structures in terrestrial animals (e.g., jaw and inner ear). Pharyngeal slits lead from the pharyngeal cavity to the outside. o They form by the inpocketing of the outside ectoderm and the evagination of the pharynx endoderm. o Used for filter feeding in some