Vertebrate Zoology Test #1

Front 1

taxonomy

Back 1

-naming and classifying species into hierarchical groups (taxa)

-developed in 18th century by Linnaeus

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systematics

Back 2

-classification system of groups linked by shared common descent

-developed in 20th century by Willi Hennig

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phylogeny

Back 3

hypothesis for evolutionary relationships of taxa

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apomorphies

Back 4

derived characters, not from ancestral characters

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node

Back 5

common ancestor of two descendant taxa

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root

Back 6

base of phylogeny

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synapomorphies

Back 7

shared derived characters by two or more taxa

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plesiomorphies

Back 8

ancestral characters

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symplesiomorphies

Back 9

characters shared by a group of organisms found in their common ancestor

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monophyletic lineage

Back 10

includes common ancestor and all descendants

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paraphyletic

Back 11

includes a common ancestor and only some of its descendants

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polyphyletic

Back 12

taxon that does not include most recent common ancestor of all its members

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clade

Back 13

a phylogenetic lineage originating from a common ancestral taxon and including all descendants

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parsimonious

Back 14

the evolutionary relationship requiring the fewest number of changes from ancestral to derived character states

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parallel evolution

Back 15

species that diverged relatively recently develop similar specializations (not common ancestry)

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sister group

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monophyletic lineage most closely related to the monophyletic lineage being discussed

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reversal

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produces similar structures in distantly related organisms (not common ancestry)

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monophyletic

Back 18

having a single evolutionary origin

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chordate notochord

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-rigid dorsal rod

-site of attachment for muscles to permit body propulsion from myomeres contraction

-vertebral column surrounds it

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chordate dorsal nerve cord

Back 20

-precursor to central nervous system

-concentrated sensory apparatus in the front of the body

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chordate postanal tail

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muscular, segmented tail expanding beyond the anus

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chordate endostyle

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-ventral longitudinal groove along pharnyx

-secretes mucus to trap food particles

-homologous to vertebrate thyroid gland which regulates body's metabolic rate

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chordate pharyngeal slits

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-present along pharynx

-used for filter feeding

-used for respiration O2 uptake and CO2 released by diffusion

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chordates

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classification of all vertebrates

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cephalochordata (27 spp.)

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-small filter feeders of coastal marine environments

-large surface to volume ratio because lack of large organs

-sequential contraction bends body in S shape

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urochordata (tunicata) (3000 sp)

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-marine filter feeders

-free swimming larvae

-sessile adults have highly derived body plan

incurrent siphon brings water in and excurrent releases

-similar look to cephalochordata

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cephalization

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-higher rates of activity increase tendency to explore new environments

-required specialization of head region

-protection for anterior head region

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embryonic development

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-endoderm is the inner lining of digestive tract

-ectoderm is the epidermis and nervous system

-mesoderm is the muscles, bones, cartilage, blood, notochord, vessels, and urogential tract

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neural crest

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-4th germ layer only found in vertebrates

-gives rise to structures in the head

(cranial bones and muscles, peripheral nervous system, pigment cells)

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hox genes

Back 30

-control other genes regulating longitudinal body development and segmentation

-larger sets increase ways they can interact generating new phenotypes

-1st duplication of all genes following divergence from vertebrates

-2nd duplication before evolution of gnathostomes

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vertebrae

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-cartilaginous or bony skeleton elements that surround nerve chord and notochord

-provide protection and stability

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cranium

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-protective enclosure for brain

-protects body parts exposed to new environment first

-supports complex sense organs to navigate environment

-major components include chondrocranium, splanchrocranium, and dermatocranium

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branchiomeric muscles

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-expand and contract visceral skeleton

-permits suction feeding

-moves water over gills for O2 absorption

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extended head

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-cephalic region extends beyond notochord

-provides physical space for brain, sense organs, and modified branchial architecture

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tripartite brain

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-larger brain with distinct 3 part arrangement

-allows detection and integration of wide range

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circulatory system

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-blood contained within vessels until they reach target tissues in which then they diffuse out

-O2 and CO2 transported into bloodstream

-oxygen is bound to hemoglobin, increasing efficiency of O2 uptake and circulation

-3 chambered heart used to efficiently pump blood in unidirectional fashion

-sinus venosus- atrium- ventricle

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myomere arrangement

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-W shape permits greater overlapping of adjacent myomeres

-greater range of body movement when muscles contract

-modified from V shape seen in cephalochordates

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gut activity

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-movement of digestive tract by penstasis

-extracellular digestion has food particles broken down first by secretion in the liver and pancreas, they are then absorbed

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kidney

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-organ specialized to remove nitrogenous waste and maintain water/ion balance

-basic unit is nephron

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photoreception and vision

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-adaptions for detection of light

-pineal gland

-well developed eyes with retina, cones, and rods

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chemoreception

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-specializations for detection of dissolved molecules (low chemicals in water)

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lateral line system

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-sensory system that detects water movement by pressure changes

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electroreception

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ability to detect electrical impulses generated in biological tissues

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vestibular apparatus

Back 44

-organ of balance

-indicates position in space by fluid movement in tubes connected to organ

-secondarily modified in land vertebrates and some fishes to detect our displacement

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cambrian vertebrates

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->500mya

-small, soft bodied fish shaped animals

-cranium with sensory structures indicates presence of neural crest

-W-shaped myomeres and notochords

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myxinoidea (hagfishes)

Back 46

-75sp

-most primitive living vertebrates with mix of ancestral and uniquely derived traits

-evolved 500 mya

-jawless fishes with eel like body form

-15 gill slits

-one semicircular canal

-accessory hearts in liver and tail

-only rudiments of vertebrae

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hagfishes head

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-3 pairs of head tentacles are tactile organs (barbels)

-used in pray search

-mouth has 2 rows of teeth like structures made of keratin (not avg vertebrate teeth)

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hagfishes feeding behavior

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-deep sea cold water scavengers of carcasses but can pursue live prey in sediment

-can tie body in knot to gain leverage when shearing off flesh

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hagfishes defensive strategy

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-secretes massive amounts of mucus and protein from unique slime glands when disturbed

-causes prey to let go because they are unable to properly breathe

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petromyzontoidea (lampreys)

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-40 sp

-jawless fishes considered closest living relative of gnathostomes

-mix of primitive and highly derived adaptations

-possesses arcualia (cartilagenous elements of dorsal neural arches)

-large eyes

-7 external gill slits

-2 semicircular canals

-heart innervated by CNX (vagus nerve)

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larval lamprey (ammocoete)

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-use pharynx for filter feeding and respiration

-they show key transition in function of pharnyx

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adult lamprey

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-specialized for parasitic lifestyle

-simple digestive tract linked to fluid diet

- oral hood with teeth like spines provide suction and abrasion

-spiky tongues used as rasp to scrape off skin

-oral gland secretes anticoegulant

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flow-through respiration in lampreys

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-water passes through mouth into respiratory tube where it exchanges O2 with gill filaments

-pumped out through external gill slits

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tidal respiration in lampreys

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-water pumped into pharynx via external gill slits by suction created by elastic recoil of branchail basket

-velum prevents water from entering esophagus

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invasion ecology

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-P. marinus invaded Great Lakes in early 1900s- led to decline of economically important fishes

-this is examples of species declination from exotic species introduction

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conodonts

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-evolved in late cambrian (500 to 200 mya)

-soft bodied jawless vertebrates with unique paryngeal morphology

-tooth-like structures composed of apatite

-s teeth for grasping, p teeth for crushing

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ostracoderms

Back 57

-multiple lineages of jawless vertebrates

-more derived then living agnathans

-arrived (460-360 mya), declined with extinction of small soft bodied prey at end of devorian

-first verts with bony tissue

-lacked true jaws, but some had moveable mouth plates that's not seen today

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original functions of bone

Back 58

-protection from predators

-insulation of electroreceptor organs

-regulation of key minerals (calcium & phosphorus)

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odontodes

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-skin elements homologous with true vertebrate teeth

-placoid scales of living sharks closely resemble odontodes of ostracoderms

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gnathostomes

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-larger size, greater activity, and increased complexity

-2nd hox gene duplication

-evolved true jaws (modified branchial apparatus)

-expanded into new ecological niches

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derived features of gnathostomes

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-jaws (usually with teeth)

-gill rakers (block food from entering gills)

-hypobranchial muscles permits suction feeding

-2 sets of paired fins helps improve locomotory performance

-2 olfactory tracts for 2 distinct nostrils increases sensitivity to dissolved chemicals

-first gill slit is spiracle

-3 semicircular canals

-centrum with ribs

-horizontal septum

-myelin sheaths on neurons

-conus ateriosus on heart

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gnathostome fins

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-enlarged caudal fins produce thrust

-unpaired dorsal and anal fins control roll (rotation around long axis) and yaw (left and right swing)

-paired pectoral and pelvic fins control pitch (up and down tilt) and braking/accessory thrust

Front 63

evolution of jaws

Back 63

-jaws evolved from branchial gill arches

-first gill arch became upper and lower jaw

-mandibular arch: pelatoquadrate cartilage and mandibular cartilage

-first gill slit became spiracle (allows water to enter pharynx during feeding)

-second gill arch became hyoid arch

-new branchial muscles evolved for respiration

-strong suction brings in more water

-selection for larger muscles required larger gill arch

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mallatt hypothesis

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mobile jaws are by product of selection for gill ventilation

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secondary functions of jaws

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-grasping and manipulation of food items

-non food object can be manipulated for other purposes

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placoderms

Back 66

-diverse group of extinct primitive gnathostomes (early silurian 440-360 mya)

-mostly bottom dwellers (benthic)

-thick bony shield over anterior half of body

-joint between head and truck allowed head to lift when feeding

-some had truth teeth others had fake made of bone

-earliest known verts with live birth (shown by fossils)

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acanthodians

Back 67

-early ordovician (450-280 mya)

-extinct group closely related to true bony fishes -evolved in oceans but diversified in freshwater habitats

-up to 6 pairs of ventrolateral fins in addition to pelvic and pectoral fins

-fusiform bodies and heterocercal tail suggest active midwater (pelagic) lifestyle

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density and viscosity

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water is denser and more viscous than air

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oxygen content

Back 69

-water has lower oxygen content than air

-requires efficient mechanisms to extract it

-saltwater has lower O2 than freshwater

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heat conductivity

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-water has higher heat conductivity than air

-heat readily transferred to water

-hard to maintain body temp above background water temp

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obtaining O2 with gills

Back 71

-gills are major gas exchange organs of aquatic vertebrates derived from pharynx

-usually receive water unidirectional from mouth, covered by operculum in bony fishes

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gill structure

Back 72

-gill arch is the skeletal structure derived from pharyngeal bars of chordate pharynx, support gill filaments

-gill filaments are thin vascularized structures attached to gill arches
(contain afferent and efferent arterioles)

Front 73

capillaries (secondary lamellae)

Back 73

blood vessels linking the afferent and efferent arterioles within each gill filaments

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counter-current exchange

Back 74

-O2 in water diffuses into blood capillaries of the secondary lamellae

-ensures diffusion gradient maintained along secondary lamellae

-always higher concentration of oxygen in water relative to secondary lamellae

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sequence of blood flow through the gills starting at conus arteriosus

Back 75

afferent branchial artery, afferent arteriole, capillary, efferent arteriole, efferent artery

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labryinth

Back 76

-this organ is in the back of the mouth

-rich in the blood vessels

-allows O2 to move into gills

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buccal pumping

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-water pumping through gills by opening and closing mouth

-suction moves water into mouth

-positive pressure forces it across gills

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ram ventilation

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-O2 intake by swimming with mouth open

-many sharks and predatory bony fishes

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adjusting buoyancy

Back 79

-ordinarily most fish are neutrally buoyant

-water pressure changes with depth

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swim bladder

Back 80

-air filled sacs to regulate buoyancy

-to change depth in water column they must change air volume in the bladder

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buoyancy

Back 81

-when descending outside water pressure increases and bladder compresses

-must add gas to bladder to prevent bladder from collapsing

-when ascending hydrostatic pressure decreases and bladder expands

-must release gas to prevent bladder from over expanding

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physostomous fish

Back 82

-retain connection (pneumatic duct) between gut and swim bladder

-add air to bladder by gulping air at surface

which then enters via digestive tract

-burping allows fish to rise

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physoclistous fish

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-lack pneumatic duct-causes the swim bladder is disconnected from digestive tract

-cannot add air bladder by gulping at surface

-derived condition

-ventral part of swim bladder linked to special capillaries (rete mirabile)

-gas gland secretes lactic acid and CO2 increasing blood pH

-as blood acidifies, hemoglobin releases O2 into blood

-when O2 pressure in rete mirabile > swim bladder, O2 diffuses into swim bladder

-excess O2 released through muscular valve (ovale) back into blood

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bohr effect

Back 84

hemoglobin reduces affinity for O2

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root effect

Back 85

hemoglobin cannot bind as much O2