Vertebrate Zoology Chapter 12 Living on Land PDF

Living on Land Chapter 12 Modifications for Living on Land Bones and support Allometry Locomotion Eating Breathing Pumping blood Sensory systems Conserving water Body temperature Reproduction  Body Support – The Skeleton Amniotes have bones that are arranged as cylindrical...

Living on Land Chapter 12 Modifications for Living on Land Bones and support Allometry Locomotion Eating Breathing Pumping blood Sensory systems Conserving water Body temperature Reproduction  Body Support – The Skeleton Amniotes have bones that are arranged as cylindrical Haversian systems - concentric layers around blood vessels Lamellar (aka Compact) bone - External, dense part of bones Cancellous bone - Internal, spongy part of bones Bone in joints is cancellous and articular cartilage covers the ends of bones (reduces friction) Joint capsule surrounding the joint that contains synovial fluid Body Support – The Cranial Skeleton Bony fishes have extensive dermal skull bones that are retained in tetrapods Fish have bones that connect their heads to their pectoral girdles (supracleithral bones) Tetrapods lost those bones (allows for independent head movement)  Body Support – Vertebrae and Ribs Allow the body to bend instead of twist when muscles contract Zygapophyses - interlock on vertebrae to resist twisting and bending Atlas and axis are cervical vertebrae in mammals that allow the head to move Thoracic (trunk) vertebrae - Bear ribs Sacral vertebrae - Vertebrae attached to the pelvis Caudal vertebrae - In the tail Ribs also provide body support and are attached to thoracic vertebrae  Body Support – Axial Muscles Used for locomotion in fish Two functions in tetrapods: postural support and lung ventilation Still used for bending walking motion in salamanders, lepidosaurs, and crocodylians Watch a salamander walk on a treadmill | Science News – YouTube Mammals and birds move their limbs instead of flexing their axial muscles Tiger Walk Cycle - YouTube Body Support – Axial Muscles 2 layers of hypaxial muscles in bony fish 3rd layer in tetrapods - transverse abdominus - is used to expel air from the lungs in amphibians Rectus abdominus muscle (abs) is a new muscle in tetrapods - mostly for posture Costal muscles in the ribcage are used for respiration Transversospinalis muscles go between vertebrae and help with postural stability  Body Support – Appendicular Skeleton Limbs and Limb Girdles Sharks have a simple pectoral girdle (coracoid bar) Bony fish have a more complex pectoral girdle Scapulocoracoid joins the clavicle and cleithrum, which are connected to the dermal skull roof Pectoral girdle is not connected to the vertebral column though the pelvic girdle is connected (generalized tetrapod skeleton) Body Support – Appendicular Skeleton: Limbs & Limb Girdles Tetrapod limbs are derived from fish fins As the limbs and their connections to the rest of the skeleton evolved, limb bones took on distinct roles and many bones were lost The humerus and the femur were already connected to the radius and ulna in the forelimb, the tibia and fibula in the hindlimb Muscular connections between these bones began to change and allowed the limbs to be used for terrestrial locomotion The ankle was originally composed of many small bones arranged in two rows, but gradually many of these small bones were lost The first animals to get close to walking on land had eight digits on each limb Over time, some of these digits were lost Body Support- Appendicular Skeleton: Limbs and Limb Girdles Tetrapod pelvic girdle articulates with the sacral vertebrae Tetrapod pectoral girdle is not attached to the head or to the vertebral column Muscles and connective tissue attach them  Body Support – Size and Scaling Allometry - the scaling relationship between the size of a body part and the size of the body as a whole Cross-sectional area of a limb bone that supports an animal’s weight on land Large animals have proportionally thicker limb bones than smaller animals Stress on bones is higher in large animals Stand and move differently Eating How did bony fish eat? Tetrapods have large, muscular tongues that they use to manipulate food in their mouths and move it to the throat Some salamanders, frogs, and lizards can project their tongues to catch prey Salivary glands Adductor mandibulae m. - jaw-closing muscle Depressor mandibulae m. - mouth-opening, runs from back of jaw to the skull Sphinctor colli m. - swallowing food, surrounds the neck Used for facial expressions in mammals  Assumed lungs evolved in fish that lived in Positive Pressure stagnant water with low O2 Instead, maybe evolved to supplement gill Breathing breathing in very active fish Amphibians use positive-pressure to inflate on Land the lungs Amniotes use negative-pressure to get air Expand the ribcage, creates negative Negative Pressure pressure, and sucks air into the lungs Air is expelled by compressing the abdominal cavity by putting the ribs back to a resting position, contracting the lungs, contracting the transverse abdominus muscle Lungs in amniotes are subdivided to increase surface area Amniotes have a long trachea that is strengthened by cartilaginous rings  On land, blood tends to pool in low spots and has to be pumped up to the heart against gravity Valves in limb veins prevent backflow Double circulation Pumping Blood Pulmonary circuit brings deoxygenated blood to the lungs Systemic circuit takes oxygenated blood to the body Atrium is divided into the left and right side Right side of the heart receives deoxygenated blood returning from the body via the systemic veins Left side of the heart receives oxygenated blood returning from the lungs via the pulmonary veins Ventricle either has a fixed barrier (crocodylians, birds, and mammals) or barriers that form as the heart contracts (turtles and lepidosaurs) Crocodylians, birds, and mammals have coronary arteries that bring oxygenated blood to the ventricle of the heart Not in amphibians and non-avian reptiles because the ventricle is not permanently separated Pumping Blood Lymphatic system Collects fluid (plasma) leaked from the capillaries and returns it to the circulatory system Lymph nodes filter lymph and can catch foreign materials like cancer cells or bacteria  Sensory Systems - Vision Muscles Vision is more acute in air than in water move because air causes less disturbance to light the lens Terrestrial vertebrates focus their eyes by changing the shape of the lens Aquatic vertebrates change the position of the lens Terrestrial vertebrates also have Muscles Eyelids change shape of Lacrimal glands (produce tears) the lens Nasolacrimal duct (drains the eyes into the nose) Sensory System - Hearing Sauropsid Water movement stimulates hair cells of the lateral line system Middle ear consists of the tympanum (eardrum) Receives low energy sound waves and amplifies them to the inner ear Stapes (sauropsids) or ossicular chain (mammals) transmit sounds to the oval window Oval window produces waves in the fluid in the inner ear, which stimulates hair cells in the organ of Synapsid Corti in the lagena or cochlea Then gets transmitted to the CNS Auditory or Eustachian tube connects the middle ear to the pharynx, and air flows in and out with changes in pressure How the Ears Work - Nemours KidsHealth - YouTube Sensory Systems - Olfaction Olfactory receptacles are located in the nasal passages of vertebrates Ethmoturbinates - Thin bones where most olfactory receptors are located in mammals Vomeronasal organs - Olfactory organ in the anterior roof of the mouth in tetrapods How Bucks Use the Vomeronasal Organ During the Rut - YouTube Snake's Secret Weapon | World's Deadliest – YouTube  One issue with living on land is that you are not constantly absorbing water, Conserving Water and you lose it through evaporation, urine, and feces Outer layers of skin in vertebrates synthesizes keratin and forms the stratum corneum, which protects the skin, and along with lipids in the skin, helps it retain water Tetrapods also have kidneys that excrete wastes as either semisolids or concentrated liquids New structures in tetrapods Bladder Ureter  Controlling Body Temperature Thermoregulation is essential for tetrapods Generally, maintain body temperature higher than the air temperature Endothermy - Create body heat using the chemical reactions of metabolism Ectothermy - Get heat from the environment through sunlight or sitting on a warm object  Ancestral form Sun is the primary source of heat for most ectotherms Gain of heat Infrared radiation is emitted by all animate and inanimate objects according to their surface temperature Gain or loss of heat Convection transfers heat between an animal and a fluid (air) Gain or loss of heat Conduction allows heat to be transferred between a body and a substrate Gain or loss of heat Evaporation of water to the environment Heat loss Ectothermy Metabolic heat gain Comparatively low heat gain  Exchange energy with the environment in the same ways as ectotherms Have a 7-10x higher metabolism than ectotherms Endothermy During cellular metabolism, chemical bonds are broken Some of the energy is lost as heat, which is used to maintain body temperature What are some of the advantages of endothermy? Why would that strategy have evolved? Heterothermy Variation in body temperature Temporal heterothermy - Allow body temperature to fall for hours to weeks Regional heterothermy - Variation in temperature of different tissues Mammals in the winter Some sharks, large fish Reproduction