Biology of Vertebrates Week Two Notes
Biology of Vertebrates Week Two Notes BZ 214
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This 12 page Class Notes was uploaded by Kenzie Busick on Thursday January 28, 2016. The Class Notes belongs to BZ 214 at Colorado State University taught by Shane Kanatous in Winter 2016. Since its upload, it has received 62 views. For similar materials see Animal Biology- Vertebrates in Biology at Colorado State University.
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Date Created: 01/28/16
Biology of Invertebrates Week Two 01/26/2016 ▯ Chordates Approximately 55 thousand species identified Extreme diversity and ecological niches amongst vertebrates o Occupy every ecological niche on the earth Shape the ecosystem (top predators and largest consumers) In comparison-> 10,000 species of Cnidarian, 20,000 Flat Worms, 95,000 Molluscs, and 1 million species of Arthropods o put into perspective that the vast majority of the animal kingdom are invertebrates ▯ Chordate Shared Derived Characteristics Four key characteristics (must be present at the same time): o Notochord (skeletal element that muscles attach to in order to allow movement- made of cartilage, NOT a backbone) o dorsal hollow nerve chord (sits dorsally in comparison to the notochord, NOT a backbone- sits within the spinal backbone) o pharyngeal gill slits (respiration and/or filter feeding) OR endostyle (gland that secrete mucous like material for filter feeding- homologous with the thyroid gland) o muscular post-anal tail (also allows for mobility) o Notochord & dorsal hollow nerve cord unique to chordates Positioning of the nerve chord that is unique (dorsal) ▯ Germ Layers Ectoderm- epidermis (skin), *nervous system Mesoderm- skeletal elements & muscular system (movement) o Big difference between diploblastic o Excretory system Endoderm- generate internal organs Protostomes vs Deuterostomes Eight cell stage in protostomes is spiral & determinate (already determined to what it would become; ex- muscle tissue) Eight cell stage in deuterostomes in radial & indeterminate (still has the potential to become anything) Development of blastopore o Protostomes: blastopore becomes the mouth o Deuterostomes: blastopore becomes the anus ▯ Stem Cells Harvest from the embryo Major problem: If person has genetic disorder -> so do the stem cells ▯ Adult Tissue Types in Animals 5 Major o Epithelial (outer lining of organs and the body) o Connective (connects things; ex- tendons & ligaments) o Vascular (vessels that move blood) o Muscular (smooth & skeletal) o Nervous (regulates how the organism responds to environment & movement/metabolism) Muscular and Nervous are unique to animals and not plants Tissues combined to form larger units called organs ▯ Organ systems in adult vertebrates Integument (skin- extremely important: maintain homeostasis within the body) Skeletal (adds support to the body) Muscular (movement) Digestive (obtain nutrients from external environment) Respiratory (oxygen in and CO2 out) Circulatory (connects the cells of the body and the organ systems, removes waste, carry chemical messengers) o Can think of as the internal highway of the body Excretory (manage and remove metabolic waste) o Kidneys (metabolic waste) & lungs (CO2) Reproductive (pass on genetic information, produce gametes) Sensory (body react to internal/external environment Endocrine (hormones: chemical messengers that help regulate internal body) o Works with sensory and regulate each other in order to maintain internal body ▯ Integument Covering of body; consists of 3 parts o Epidermis – outer layer of the body (dead skin cells that add a protective layer of the body such as scales) o Dermis – living layer of the skin Living cells, nerve endings, certain glands o Hypodermis- large role in mammals and birds – where you find circutaneous fat (insulation that allows birds and mammals to be endothermic/keep metabolic heat inside body) Functions o Secretes various bodily products (mucus, poison, sweat) o Prevent water loss o Protect from pathogens, predators, chemicals o Exchange comounds o Senses (integration with nervous system) o Involved in thermoregulation o Sometimes used in respiration Skeletal Function in support, movement, protection, and storage of calcium and phosphate o Axial: consists of bones o Appendicular: consists of the bones of the limbs Gnathostomes first to have appendicular skeleton Six types of tissues can become mineralized(hard parts) in vertebrates o Cartilage- least mineralized o Bones- more mineralized o Dentine- components of the teeth are the most mineralized (hardest) parts of the body Easier to find fossilized teeth than anything else o Enamel- outside of the tooth o Enameloid- sits below the enamel, some organisms replace the enamel o Cementum- secure the tooth in place Bone is divided into two types o Dermal Formed in skin without cartilaginous precursor Earliest type of vertebrate bone; found originally in ostracoderms (jawless fish) Most skulls bones are dermal o endochondral Formed in cartilage then replaced with bone Bones in arms and legs (appendicular skeleton) First seen in bony fish ▯ Muscular Function in movement, either body of internal organs o Movement of body is voluntary o Stomach digesting food in involuntary Three types of muscle o Skeletal or striated: muscle that does not move without brain input (voluntary) 3 groups- fast twitch (white in color, anaerobic base for metabolism; ex- sprinting, jumping) slow twitch (red in color, fatigue resistant/endurance; ex- running a marathon), intermediate (pink in color, contract fast then slow or slow then fast, anaerobic but can produce more power than slow twitch; ex- mile runner/speed and endurance) o Smooth: lack striation- involuntary movement o Cardiac: combination of the other two (aspects of voluntary and striation) Only type of muscle that can generate its own rhythm/pace maker Only found in the heart ▯ Digestive Break down food products in absorbable components to bring into body and use for building blocks and fuel Mouth, esophagus, stomach, intestine, cecum, large intestine, anus Size or even presence of these structure depends on diet of organisms o Feeds on something soft of fluid will have a simpler digestive system than something that feeds on meat Parasitic forms have greatly reduced digestive systems (ex- lamprey) Herbivorous forms have large and elaborate digestive systems (ex- cow) o No animals posses enzymes to break down plant material o Must have bacteria in digestive system to break it down ▯ Respiratory Functions to allow exchange of gases between body and environment Occurs in different ways depending on size and habitat of organism As you become more complicated you have an increase in metabolism and needs more oxygen Increase metabolism -> more surface area to extract oxygen from its environment Circulatory Functions to transport gases (O2 and CO2), nutrients, hormones, and heat throughout the body Certain cells also participate in immunological functions in response to foreign substances and pathogens Differs vert from animal kingdom- ALL have a closed circulatory system Capillaries are the sit of gas exchange *all exchange occurs across capillaries Blood pumped by heart that can have 2-4 chambers o Deoxygenated blood pumps through the heart-> becomes oxygenated then goes to the rest of the body Low pressure circulatory system (gills and lungs are very delicate and cannot except high blood pressures) ▯ Excretory Functions to remove metabolic waste (primarily urea and derivatives), maintain water balance, and regulate various ions Primary organ: kidney in tertrapods; in aquatic organisms, gill and skin also play a large role As organisms move from water to land= increase pressure to maintain water balance (kidneys have to become more efficient) ▯ Reproduction Two types of gametes: sperm(males) and eggs(female) Organisms may lay eggs (oviparous) or bear live young (viviparous) o Passing on genetic information is the key to adaptive success- extremely important Sensory Function to integrate information and response throughout the body; sense event in the external environment Mainly the nervous system o Can be divided into two parts: Central nervous system- brain and spinal cord Peripheral nervous system-nerves that extend out from the spinal cord Can also be broken down into the somatic (voluntary motion) and autonomic (involuntary motion) Autonomic can be divided into sympathetic and parasympathetic Brain divided into three general structures o Brain integrates and processes information Hindbrain Midbrain Forebrain 3 parts are found in ALL vertebrates, only thing that changes is which portion of the brain is enhanced ▯ Endocrine Function in regulating and controlling various functions via chemicals and hormones o Balances blood sugar (long term effect/maintains a longer response) Regulate internal environment Hormones released by endocrine glands ▯ HOX genes Help lay out the basic body plan for an animal Found throughout the animal kingdom Set up head to tail organization Regulate signaling cascades-> does not bring an immediate response but tells other genes to turn on Key determining factors are o Concentration o Location in which genes initiated o Timing o Target gene specificity As body becomes more complicated we duplicate the amount of HOX genes More nerves in a smaller area Unique vertebrate characteristic is the myelin sheath ▯ Vertebrate brain Further extension of the dorsal hollow nerve cord Forebrain- two parts o diencephalon (pituitary gland, hypothalamus and the pineal organ) o telencephalon (develops in association with olfaction and other sensory modalities- cerebrum of higher vertebrates) midbrain- regulates vision hindbrain- two parts o metenchephalon (regulates motor activity; in jawed vertebrates develops an outgrowth; the cerebrum) o Myelencephalon or medulla oblongata (regulates respiration, balance and orientation) The development of jaws was a critical event in vertebrate evolution because it ushered in a transition to a predatory lifestyle Difference in brain development depends on the environment ▯ Jawless vertebrates and the Origin of jawed vertebrates Ostracoderms- were the earliest “definite” vertebrates, first appearance of bone (dermal), Conodonts- some of the earliest vertebrates, appeared to have tooth-like fossils (didn’t have a jaw) Figure 2.1 and 2.4 in the text Vertebrates represent a new more active lifestyle o The earliest ostracoderms possessed a muscular pharyngeal pump for forcing water over the gills o Amphioxus (a non vertebrate chordate) uses ciliary motion to move water- couldn’t be used for a larger and more active organism ▯ Appearance of Bone Calcium phosphate- primary mineral component of vertebrate bone o Resistant to lower pHs, important to energy Calcium carbonate- most common mineral in invertebrates but some do have calcium phosphate o Very sensitive to lower PHs, important for every pathway in the body Jawless Craniates and vertebrates Extant- hagfishes (craniate) and lampreys (1 vertebrate) Extinct- ostracoderms There are no fossils attributable to hagfish until the Carboniferous- but possess many characteristics that indicate that they must be primitive Many groups of ostracoderms o They start to become more active o Adaptions to make them more fish like Extant Jawless craniates and vertebrates o Myxinoidea (hagfishes) Do not possess vertebrate Single terminal nasal opening Have small paired eyes but no extrinsic eye muscles or pineal eye (distinguishes from other vertebrates) Cranium made of a fibrous sheath rather then cartilage or bone One semicircular canal (do not orient well) No lateral line system (instead have a primitive system of canals) In contrast to vertebrates they have accessory hearts in the liver and tail regions Body fluids are isosmotic with seawater Limit the environment that hagfishes can swim in o Petromyzontoidea (lampreys) Possess vertebrae Parasitic (feed on the blood of other animals) Well developed eyes Only vertebrate with a single nasal opening Parasympathetic nervous system Well developed kidneys allow them to inhibit different environments Larval stage- ammocoete ▯ Rise in jawed vertebrates The development of jaws was a critical event in vertebrate evolution because it ushered in a transition into predatory lifestyles Origin of jaws o Arose from an adaption of the first gill arch (converted gill arches into jaws) o Made from neural crest derived cartilage just as the branchial arches are Derived from the ectoderm (why it isn’t considered a 4 th germ layer) Brought new abilities o Ability to grasp prey o Ability to create better suction (begin to identify the difference of the environments the animals live in) Allowed vertebrates to reach much larger sizes and quickly replace jawless vertebrates Earliest jawed vertebrates o Placoderms Theories behind the evolution of jaws o Since it was an adaption of the gill arch, a lot of the organisms that were before this were filter feeders, as these animals began to adapt -> mutations came in to allow them to pull more water in -> pulling more food in -> more energy to reproduce and that adaption gets passed on Adaptation to get more oxygen ▯ With jaws, come teeth Kinds of teeth o Tooth whorl- found in cartilaginous fish, since they lack dermal done their teeth form within the skin that rests on the jawbone o Pleurodont- primitive condition, teeth set in shelf on the inner jaw, seen in some bony fish, modern amphibians, and some reptiles o Acrodont- tooth is fused in the jawbone, most bony fish & some reptiles o Thecodont- teeth are set in a socket and held in place by ligaments, seen in crocodiles, dinosaurs, and mammals ▯ ▯
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