Bioligy 202

• means "partial chord" (acorn worm and pterobranchs)
• are worm like marine animals
• range from 2 cm to 2 m
• filter feeders
• sedentary
• live under stones, in burrow, or in tubes if in shallow water

more like chordates as they have ciliated pharengeal slits, an open cirulatory system, and a dorsal hollow nerve tube in the collar region

• name chordata comes from: the noto chord which is a rod like semi rigid organ enclosed in a sheath
• they posess: a dorsal hollow nerve cord extending the length of their body, pharyngeal slits, an endostyle (ciliated groove in the pharynx) and a mucular post anal tail.
• 3 sub phyla: urochordata, cephalochordata, craniata
• latter includes infra phyla hyperotreti and vertebrata

• 3000 spp
• sessile
• aquatic
• only larval form has all chordate characteristics including notochord
• body wall made of connective tissue called a tunic
• have a highly developed muscular pharyngeal basket used in filter feeding
• larvae are beleived to to be the prototype of ancestral chordate
• chordates evolved from this via paedomorphisis (sexual maturation of the larval form)

have well developed notochord through out their life, gill bars, segmented muscles, fish shapedbody but no vertebrae, brain or anterior sensory organs

• small (5-8cm)
• latterally flattened
• transluscent
• live in sandy bottoms of temperate costal waters
• extract food from sea water by filter feeding while burrowed in the sand with only their head exposed

• includes many extinct fish like animals as well as the hag fishes
• have a fully developed notochord and a cartelagenous skull but no vertebrae or jaws
• used to be group with lamp reys
• extant member hag fishes (class myxini) are fish like marine animals that burro in sand and mud
• they eat the inside of dead or dying fish by entering through an organisms mouth for defence they secret copious amounts of slims through special slime glands

• like other chordates as they have gill bars and segmented muscles
• have modifications allowing for increase size speed and mobility
• defining feature is there segmented vertebral column that houses the dorsal nerve chord

• jawless fish like animals like hag fish but unlike hag fish they have simple vertebrae
• larvae- mall bottom dwelling filterfeeders
• adults parasites on other fish

• 1horny teeth ----7intestine -----13respiratory tube
• 2buccal funnel --8liver----------14 velum
• 3mouth----------9gonad--------15olfactory sac
• 4tongue---------10notochord---16brain
• 5nostril----------11gill filamen---17 spinal chord
• 6pineal eye------12heart

• lamprey skin is mooth and pliable, coverd with mucous
• epidermis is a living tissue of stacked layers of epidermal cells with unicellular glands (not normally kerotinized)
• dermis is in regular layers of collagenous connective tissue with pigment cells
• hypodermis includes adipose tissue

Question 1: observe the slide of the lamprey on the side bench and identify these features( epidermal cells, collageneous tissue, adipose tissue)

Answer 1: no scale on a lamprey

• secreted and maintained by living tissue
• expand as we grow
• superior to the exoskeleton for those over 0.5 grams
• early on skeletal system made of cartelage
• chondrichthyes (sharks and rays)skeleton is always cartilage. this is a derived feature as ancestors didnt have it
• functions: skeltetal support during development, cushioning between joints, absorption and storage of mechanical energy during locomotion.
• consists primarily of chondrocytes within a matrix of collogen

• endochondral bone: develops within the cartilage from osteocytes that have inveded the cartilage (most os the skeleton)
• dermal bone: developes beneath the skin. first type of bone, seen first in ostracoderms (extinct jawless fish that carried bony armour of dermal plates
• face and cranium made of dermal bone

Question 2: how do cartilage and bone differ at the microscopic level

• Answer 2:
• cartilage: chondrocyte cell in a mixture of collagen
• bone: bone matrix deposited in concentric layers around osteonic canals

• composed of muscle fibres comprised of thousands of myofibrils
• striated muscle: (voluntary and multi nucleate) used for gross movements such as locomotion. can also maintain circulation and regulate body temperature
• Smooth muscle: (involuntary and uninucleate) occurs in the skin and the lining of the gut, blood vessels, and reproductive tracts
• Cardiac muscle: occurs in the heart and requires no innervation are branched

Question 3: how do the types of muscle differ in their microscopic structure?

• skeletal: long cilindrycal shape
• smooth: spindle shaped
• cardiac: striated and branched

• the major function of the mouth is to aquire food
• also used for taste, digestion, defence, and aggression
• the mouth and the pharynx function in vocalization

Question 4: does the lampreyhave all teh major components of a vertebrate digestive system (teeth, tongue, salivary glands, stomach, liver, and intestines)? does this have andy functional significance (think in terms of lampreys diet-blood)?

• they have a protrusable toung to suck the blood out of their prey
• have many rows of teeth to grasp the sides of fish
• have 1 pair of salivar glands which have anti coagulates to keep sucking the blood of prey
• short esophagus because they suck blood
• contain a stomach (ancestral vertebrate structure). stomach allows for storage of large feedings of larger animals or large blood feedings
• do not have a gizzards as they dont grind up food
• have intestines to absorb blood
• dont have a ceacum
• dont have a liver or galbladder because the blood is already filtered
• have a pancrease to secrete hormones

• circulatory system supplies nutrients and gases to body as well as removes wastes and excess heat (specialization necessary for those larger than a few millimeters in size)
• also helps in communication for cells (important for growth differentiation, and reproduction)
• blood is made up of: plasma, erythrocytes, and leukocytes

• Question 5: in what ways do the blood cells vary between the groups?
• Answer 5: they vary in size and nucleation (RBCs lack a nucleus)

• The Kindey: balances salts and water (osmoregulation)
• process of digestionand respiration result in the accumulation of wasts which must be removed as they are lethal. removal of these wastes involves respiration (CO2) and excretion
• most vert tissue is 1% salt content compared to that of sea water
• hag fish evolution was likely entirely marine
• basic units of the kidney: the renal corpuscle, glomerulus, renal tube

• most primitive kidney
• functional only in embryosof fishes and amphibians and in adult hagfishes (who are iso osmoticand secrete ammonia)
• contains the fewest nephrons

• functional kidney during embryonic developement in amniotes (reptiles birds and mammals)
• has more nephrons than the pronephros
• in adult fishes and amphibians kidney has mesonephric and meta nephric portions. this is called opsithonephric kidney

• functional kidney of adult reptiles birds and mammals
• helps with water consevation
• largest number of nephrons and is the most effiecient

• ammonia: highly solluble, occurs in aquatic animals
• urea: less soluble, requires some energy
• uric acid: very low solubility, but requires even more energy (used by those in very dry areas)

• percieves the external environment and transmit the intormation to th eorganism
• they participate in the regulation of the internal environment
• the nervouse system serves as a storage site for information
• nervous system is based on the elaboration of a dorsal nerve cord
• nerves are aggregations of nerve axons
• they seperate into dorsal (sensory) and ventral (motor) roots or horns
• consists of CNS, Peripheral nerves (spinal and cranial), and autonomic (sympathetic and parasympathetic)
• vertebrate brains is tripartite (3 lobes). 2 lobes divide to eventually give 5 lobes

• Sensory Neurons: carry info from a receptor to the CNS
• Motor Neurons: carry info from CNS to an effector
• Inter Neurons: co-ordinates sensory and motor neurons
• Consist of: nerve body: dendrites, axon

• Question 6: where are the cranial and spinal nerves located?
• cranial nerves are in the head
• spinal nerves are in the spinal chord
• Question 7: where do the nerves of the sympathetic system generally originate?
• at the thoracic and lumbar regions of the spinal chord
• Question 8: where do the nerves of the parasympathetic system generally originate?
• the brain and sacral region of the spinal chord
• Question 9: what are the primary functions of the 5 lobes of the brain?
• telencephalon: cerebrum division for specialization, thalamus sensory relay center, hypothalamus, hormones, and homeostasis
• diencephalon
• mesencephalon optic lobe optic reflex center, cerebellum- motor activity, pons- nerve tracks, breathing
• metencephalon medulla oblongata- reflex centers

• 4 types
• Chemoreceptors: smell and taste
• Mechanoreceptors: touch hearing and pressure
• Photoreceptors: light
• Thermoreceptors: temperature

• Question 10:what are the functions of the lens, iris, pupil, and retina?
• lense- focuses incoming light onto the retina
• iris- alters the light intensity by controlling the size of the pupil
• pupil- the whole where the light enters
• retina- light sensitive membrans processes images

• hair cells convey information pertaing to posture accelleration, and sound
• statocysts of inner ear detect orientation and movement (semicircular canals and otolith organs (utriculus, and sacculus)
• similar mechanism lets fish detect movement in the water