Animal Diversity Cheatsheet

Cheatsheet Content

1. Fundamentals of Zoology & Animal Classification 1.1. Father of Zoology Aristotle is widely regarded as the Father of Zoology due to his extensive studies and classifications of animals. 1.2. Animal Classification: Key Groups Invertebrate Animals: Lack a vertebral column (backbone). Represent over 95% of all animal species. Exhibit diverse body plans, often with exoskeletons or hydrostatic skeletons. Examples: Insects, worms, mollusks, jellyfish. Vertebrate Animals: Possess a vertebral column and an internal skeleton. Have a well-developed nervous system, including a brain protected by a skull. Exhibit bilateral symmetry. Examples: Fish, amphibians, reptiles, birds, mammals. 2. Phylum-Specific Characteristics & Examples 2.1. Class Mammalia Key Characteristics: Presence of mammary glands for milk production. Hair or fur covering the body. Warm-blooded (endothermic). Possess a diaphragm for efficient respiration. Typically viviparous (give birth to live young). 2.2. Phylum Chordata Key Characteristics (at some point in their life cycle): Notochord: A flexible rod providing skeletal support. Dorsal hollow nerve cord: Develops into the central nervous system. Pharyngeal slits: Openings in the pharynx, used for filter feeding or gas exchange. Post-anal tail: An extension of the body past the anus. 2.3. Protozoan Animals Characteristics: Single-celled eukaryotic organisms. Heterotrophic, obtaining nutrients by ingestion or absorption. Exhibit diverse forms of locomotion (pseudopods, flagella, cilia). Reproduce asexually (binary fission, budding) and sometimes sexually. Often found in aquatic environments or as parasites. Examples: Amoeba (moves by pseudopods) Paramecium (moves by cilia) Euglena (moves by flagella, can be photoautotrophic) Plasmodium (causes malaria) 2.4. Phylum Porifera (Sponges) Characteristics: Multicellular, but lack true tissues and organs. Sessile (attached to a substrate) as adults. Possess a porous body with a unique water canal system. Filter feeders, using choanocytes to create water currents and trap food particles. Reproduce both sexually and asexually (budding, gemmules). Examples: Scypha (Grantia) Spongilla (Freshwater sponge) Euplectella (Venus' flower basket) 2.5. Protozoan Diseases in Humans Malaria: Caused by Plasmodium species (e.g., P. falciparum ), transmitted by Anopheles mosquitoes. Affects red blood cells and liver. Amoebiasis: Caused by Entamoeba histolytica , leading to dysentery and liver abscesses. Transmitted via contaminated food/water. Giardiasis: Caused by Giardia lamblia , resulting in diarrheal disease. Transmitted via contaminated water. Leishmaniasis: Caused by Leishmania species, transmitted by sandflies. Can cause skin sores (cutaneous) or affect internal organs (visceral). Trypanosomiasis (Sleeping Sickness/Chagas Disease): Caused by Trypanosoma species, transmitted by tsetse flies (African) or kissing bugs (American). 3. Coelenterates & Related Concepts 3.1. Phylum Coelenterata (Cnidaria) Classification (up to classes): Hydrozoa: Typically show both polyp and medusa stages, though one may be reduced. Examples: Hydra , Portuguese man o' war ( Physalia ). Scyphozoa: Medusa stage is dominant and often large. Polyp stage is usually reduced or absent. Examples: True jellyfish (e.g., Aurelia ). Anthozoa: Only polyp stage is present; medusa stage is absent. Often colonial and sessile. Examples: Sea anemones, corals (e.g., Fungia ). General Characteristics: Radially symmetrical. Diploblastic (two germ layers: ectoderm and endoderm). Possess a gastrovascular cavity (coelenteron) with a single opening. Presence of cnidocytes (stinging cells) containing nematocysts. 3.2. Examples of Coelenterates Hydra (Hydrozoa) Aurelia (Jellyfish, Scyphozoa) Sea Anemone (Anthozoa) Corals (Anthozoa) 3.3. Sporozoite vs. Trophozoite ( Plasmodium Life Cycle) Feature Sporozoite Trophozoite Description Infective stage for humans, found in mosquito salivary glands. Feeding and growing stage, found within human red blood cells. Location Mosquito salivary glands, human bloodstream (briefly), human liver cells. Human red blood cells. Function Initiates infection in humans by invading liver cells. Consumes hemoglobin, grows, and multiplies asexually (schizogony). Shape Elongated, spindle-shaped. Irregular, amoeboid shape within RBCs. 3.4. Amoeboid and Signet Ring Stage of Plasmodium Amoeboid Stage: Refers to the developing trophozoite within the red blood cell. It grows and becomes irregular in shape, extending pseudopod-like projections. This stage actively feeds on the host cell's hemoglobin. Signet Ring Stage: An early stage of the trophozoite within the red blood cell. Characterized by a small, vacuolated parasite that pushes the nucleus to one side, resembling a signet ring. It is typically seen in the early hours of red blood cell infection. 4. Phylum Nemathelminthes & Platyhelminthes 4.1. Phylum Nemathelminthes (Roundworms) Characteristics: Cylindrical, unsegmented body, tapering at both ends. Pseudocoelomate (body cavity not fully lined by mesoderm). Complete digestive system with a mouth and anus. Covered by a tough cuticle. Most are dioecious (separate sexes). Many are parasitic, causing diseases in plants and animals. Examples: Ascaris lumbricoides (Human intestinal roundworm) Wuchereria bancrofti (Filarial worm, causes elephantiasis) Ancylostoma duodenale (Hookworm) 4.2. Phylum Platyhelminthes (Flatworms) Characteristics: Flattened dorsoventrally, unsegmented body. Acoelomate (lack a true body cavity). Triploblastic (three germ layers). Bilateral symmetry. Incomplete digestive system (except tapeworms, which lack one). Many are parasitic, some are free-living. Examples: Dugesia (Planaria, free-living) Taenia solium (Pork tapeworm) Fasciola hepatica (Liver fluke) 5. Animal Diversity & Nomenclature 5.1. Defining Animal Diversity Animal Diversity refers to the variety of animal life forms on Earth, encompassing the differences in their morphology, anatomy, physiology, behavior, genetics, and ecology. It includes the vast range of animal species, from single-celled protozoans to complex mammals, and their adaptations to various environments. Studying animal diversity helps understand evolutionary relationships, ecological roles, and the impact of environmental changes on species. 5.2. Binomial and Trinomial Nomenclature Binomial Nomenclature: A system of naming species using two parts: the genus name and the specific epithet. Developed by Carl Linnaeus. The genus name is capitalized, and the specific epithet is lowercase. Both are italicized. Example: Homo sapiens (humans), Panthera tigris (tiger). Provides a universally recognized scientific name for each species, avoiding confusion from common names. Trinomial Nomenclature: Used to name subspecies within a species. Adds a third epithet (subspecific epithet) after the specific epithet. Example: Homo sapiens sapiens (anatomically modern humans), Corvus corvus splendens (Indian house crow). Indicates distinct populations within a species that have geographical or morphological differences. 5.3. Carolus Linnaeus Carolus Linnaeus (1707-1778) was a Swedish botanist, zoologist, and physician. He is known as the "Father of Modern Taxonomy" for formalizing binomial nomenclature, the modern system of naming organisms. His major work, Systema Naturae , laid the foundation for the classification of organisms into hierarchical categories (kingdom, phylum, class, order, family, genus, species). Linnaeus's system brought order to the chaotic naming conventions of his time and remains fundamental to biological classification today. 6. Phylum Mollusca & Arthropoda 6.1. Phylum Mollusca Characteristics: Soft-bodied invertebrates, usually protected by a hard shell (though some lack shells). Triploblastic and coelomate. Possess a muscular foot for locomotion, a visceral mass containing organs, and a mantle that secretes the shell. Many have a radula, a chitinous ribbon of teeth, for feeding. Highly diverse, including marine, freshwater, and terrestrial species. Examples: Snail ( Helix ) Octopus ( Octopus vulgaris ) Clam ( Mercenaria ) Squid ( Loligo ) 6.2. Phylum Arthropoda Characteristics: Largest phylum in the animal kingdom, with over 80% of all known animal species. Segmented body, typically divided into a head, thorax, and abdomen. Possess a rigid exoskeleton made of chitin, which must be shed (molting) for growth. Jointed appendages (legs, antennae, mouthparts). Open circulatory system. Highly adapted for various habitats (terrestrial, aquatic, aerial). Examples: Insecta: Butterfly ( Papilio ), Grasshopper ( Schistocerca ) Arachnida: Spider ( Araneus ), Scorpion ( Androctonus ) Crustacea: Crab ( Cancer ), Lobster ( Homarus ) Myriapoda: Centipede ( Scolopendra ), Millipede ( Julus )