Transcript “Why Do”
“Why Do” Questions about structural and behavioral adaptations. Design Questions • You will design questions based on research in the following areas: Gills on fish Hollow bones in birds Xylem in plants Migration Hibernation Storage of food in a bulb Examples • “Why do…” for structural adaptations. Ex.— Why do roses have thorns? Produce 6 questions and write each one on an index card. • “Why do…” for behavioral adaptations. Ex.— Why do birds sing? Produce 6 questions and write each one on an index card. Gills in Fish (structural) • A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist. The microscopic structure of a gill presents a large surface area to the external environment. • Many microscopic aquatic animals, and some that are larger but inactive, can absorb adequate oxygen through the entire surface of their bodies, and so can respire adequately without a gill. However, more complex or more active aquatic organisms usually require a gill or gills. • Gills usually consist of thin filaments of tissue, branches, or slender tufted processes that have a highly folded surface to increase surface area. A high surface area is crucial to the gas exchange of aquatic organisms as water contains only a small fraction of the dissolved oxygen that air does. A cubic meter of air contains about 250 grams of oxygen at STP. For a typical freshwater oxygen concentration of 5 parts per million by mass, a cubic meter of water will contain 5 grams of oxygen. This is about 1/50th of the oxygen of the same volume of air. • With the exception of some aquatic insects, the filaments and lamellae (folds) contain blood, from which gases are exchanged through the thin walls. The blood carries oxygen to other parts of the body. Carbon dioxide passes from the blood through the thin gill tissue into the water. Gills or gill-like organs, located in different parts of the body, are found in various groups of aquatic animals, including mollusks, crustaceans, insects, fish, and amphibians. Hollow bones in Birds (structural) • Birds have a lightweight skeleton made of mostly thin and hollow bones. The keelshaped sternum (breastbone) is where the powerful flight muscles attach to the body. Birds have a smaller total number of bones than mammals or reptiles. This is because many of their bones have fused together making the skeleton more rigid. Birds also have more neck (cervical) vertebrae than many other animals; most have 13 to 25 of these very flexible neck vertebrae (this helps them groom their feathers). Birds are the only vertebrate animals to have a fused collarbone called the furcula or wishbone and a keeled breastbone. Below is a diagram of a typical bird skeleton. 1) Skull 2) Cervical Vertebrae 3) Humerus 4) Second digit 5) Metacarpals 6) Fourth digit 14) Ilium 19) Halux 7) Third Digit 15) Pubis 20) Digits 8) Radius 11) Synsacrum 16) Pelvic girdle 21)Tarsometatarsus 9) Ulna 12) Pygostyle 17) Uncinate process 22) Tibiotarsus 10) Scapula 13) Ischium 18) Femur 23) Keeled sternum 24) Coracoid 25) Furcula (or wishbone) Xylem in Plants (structural) • In vascular plants, xylem is the tissue that carries water up the stem. In trees, it constitutes wood, hence the word is derived from the Greek word for "wood". Together with phloem, xylem is one of the two transport tissues of plants. Cross section through the stem of a magnolia plant, showing xylem vascular tissue for transporting water and mineral nutrients from the roots to the main body of the plant. Cross section of vascular bundle in wood (xylem cells visible). Migration Mexican free-tailed bats migrating south to Central America and Mexico during the winter. (picture on the left) • Animal migration is the relatively long-distance movement of individuals, usually on a seasonal basis. It is a phenomenon, found in all major animal groups, including: birds, mammals, fish, reptiles, Wildebeest Connochaetes taurinus A christmas island red amphibians, crossing a river in East Africa. Migration, crab on its migration to seemingly timed to coincide with the insects, lay eggs (Indian Ocean). and crustaceans. annual pattern of rainfall and grass growth. • The trigger for the migration may be local climate, local availability of food, the season of the year or for mating reasons. • To be counted as a true migration, the movement of the animals should be an annual or seasonal occurrence, such as birds migrating south for the winter, or a major habitat change as part of their life, such as young Atlantic salmon leaving the river of their birth when they have reached a few inches in size. (Behavioral Adaptation) Hibernation(Behavioral Adaptation) Northern Bat hibernating in Norway • Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and/or lower metabolic rate. Hibernating animals conserve energy, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate. Black bear mother and cubs "denning“. • Although often associated with cold temperatures, the root purpose of hibernation is to conserve food during a period when sufficient food is scarce. It is the animal's slowed metabolic rate which leads to a reduction in body temperature and not the other way around. Hibernation may last several days, weeks, or months depending on species, ambient temperature, time of year, individual animals body condition, and fur on the animal's body. Storage of food in a bulb (Structural) Shallot bulbs • A bulb is a short stem with fleshy leaves or leaf bases. The leaves often function as food storage organs during dormancy. Ex. onion, garlic, lilies, tulips. Tulip bulb and development • A bulb's leaf bases, known as scales, generally do not support leaves, but contain food reserves to enable the plant to survive adverse conditions. At the center of the bulb is a vegetative growing point or an unexpanded flowering shoot. The base is formed by a stem, and plant growth occurs from this basal plate. Roots emerge from the underside of the base, and new stems and leaves from the upper side.