Zoology (animal body plans)

• Epithelial tissue is a type of body tissue.
• Connective tissue is a type of body tissue.
• Nervous tissue is a type of body tissue.
• Muscular tissue is a type of body tissue.
• An animal is a living organism that is multicellular, eukaryotic, heterotrophic, and lacks cell walls.
• Multicellular means an animal is made up of many cells or (more than one cell).
• Eukaryotic is a term to describe a cell that has a membrane-bound nucleus, and membrane-bound organelles.
• Heterotrophic means an organism that consumes autotrophs, or other heterotrophs.
• Animals have cell membranes but no cell walls.
• Animals are made up of a complex system of cells.
• Cells grouped together make up tissues.
• Tissues grouped together make up organs.
• Organs grouped together make up organ systems.
• Symmetry in animals refers to the way in which a plane or planes of axis can divide the body.
• Animals with radial symmetry can be divided into similar halves by many planes, examples include jellyfish, sea urchins, sea anenomes etc.
• Animals with bilateral symmetry can be divided into equal left and right halves along the mid-sagittal plane, and exhibit cephalization (they have a head with a brain).
• When studying the anatomy of animals, it is necessary to use terminology to describe directions, planes, and other points of reference.
• Anterior/Posterior: A direction on an animals body referring to towards the head and/or tail.
• Dorsal/Ventral: A direction on an animals body referring to towards the spine or belly.
• Medial/Lateral: A direction referring to towards or away from the midline or mid-sagittal plane of the body.
• Distal/Proximal: A direction referring to farther away from or closer to another point of reference.
• Sagittal plane: An imaginary line or axis that goes through the body separating left and right halves.
• Frontal plane: An imaginary line or axis that goes through the body separating dorsal and ventral halves or sections.
• Transverse plane: An imaginary line or axis that goes through the body separating anterior and posterior halves or sections.
• Oral/Aboral: For animals with radial symmetry, oral refers to the mouth side, aboral is opposite of oral.
• After fertilization of an egg occurs, the egg becomes a zygote, then a zygote begins dividing its cells in a process called cleavage.
• Some animals (like echinoderms and chordates) exhibit radial cleavage, in which the cleavage planes are symmetrical.
• In protostomes, the blastopore develops into the mouth, which is how most invertebrates such as annelids, mulluscs, and arthropods develop.
• In most animals, the blastula develops further into a two-layered organism called a gastrula.
• A true coelom or body cavity allows much more flexibility and space for internal organs.
• Larger and more complex organisms have a coelomate body cavity.
• All of the body tissues of animals are made up of one of the four basic tissue types.
• In coelomate animals if the coelom forms from sections of mesoderm that pinch off from a region located at the terminal end of the endoderm, this pattern of development is referred to as enterocoelous development.
• In a true coelom or body cavity, the mesoderm completely lines the endoderm and the ectoderm.
• In deuterostomes, the blastopore develops into the anus, which is how echinoderms and chordates (vertebrates) develop.
• Inside the blastula is a fluid-filled cavity called a blastocoel.
• In most animals, a third germ (tissue) layer develops after the gastrula stage called the mesoderm.
• Some animals such as the sea anemone never advance beyond the gastrula stage.
• In a sea anemone, the opening or blastopore becomes the opening to its gut, which is called the gastrovascular cavity.
• The gastrocoel (cavity inside the gastrula) develops into the digestive tract in most adult animals.