Vertebrate Zoology - Exam 2

What are the two taxon groups in Osteichytes?

Sacropterygii (lobe-finned fish) and Actinopterygii (ray-finned fish)

Name the characteristics of all Osteichytes

1. Evolution of an endochondral skeleton (derived) and dermal bone (inherited)

2. Bony operculum

3. Fin rays with lepidotrichia (derived from dermal bone)

4. Enamel percursor —> enamel in sacropterygii and ganoine in Actinopterygii

5. LUNGS!

What are air-breathing mechs in fish. Think about how each are done

1. Lungs (branched from gut) 

2. Intestine

3. Lining of mouth 

4. Reinforced gills 

What are the characteristics of Actinopterygii that differ from Sacropterygii? 

1. Tribasic fin (3 bones that intersect) - less mobile, dermal fin rays 

2. Scales with ganoine (enamel precursor) 

3. Mobility of upper jaw bones - maxilla and premaxilla 

4. Pharyngeal jaws - teeth on upper jaw & gill rakes inside (help pull food into mouth) 

5. Brain develops by eversion of neural tube (think outwards)

6. Loss of lung function - oxygenated and deoxygenated blood are intermingled 

What are the charactersitics that Sarcopterygians have that differ from Actinopterygians?

1. Monobasic fin - more mobility, basal and radial bones derived from endochondral bone

2. Scales with cosmine (from dentine)

3. Immobile upper jaw

4. No pharyngeal jaw 

5. Brain develops in evagination of neural tube (think inwards)

6. Lung function

What are some characteristics the Telost clade in Actinopterygii have?

1. Homocercal (same) caudal tail fin

2. Gas bladder provide bouyancy - swim bladder makes them neutrally bouyant 

3. Thin, overlapping scales which creates smoothness regardless of the way the fish bends 

What is the difference between physotomous and physoclitous fish?

Physotomous fish - have a swim bladder connected to their gut - they inflate by gulping air and deflate by burping air - which aids with faster/better control of bouyancy 

• connects to the idea that these fish had ancestors with something similar to lungs 

Physoclitous fish - Closed swim bladder and gas is diffused through blood circulation 

• More derived character- no tube and there is movement through the blood. This is regulated by fish with pH (more acid means gas release of CO2 and Lactic acid) 

Describe reproduction in Teleost

Primarily external fertilization, some have a haphazard form known spawning, others protect the fertilized egg until development known as nesting 

• Seahorse have internal fertilization but it is ovoviviparous and there is no placenta 

Describe sex determination in Teleost

1. Genetics are known as Gonochorism (no sex change)  

   1. XY = male is heterochromic 

   2. ZW = female is heterochromic 

2. Hermaphroditic fish 

   1. Protandrous = Male first and female later 

   2. Protogynous = Female first and male later 

   3. Some can maintain both female and male gonads aka simultaneous 

Explain locomotion in Teleost

2 dimension - Lift (gas bladder aids this) and Thrust - fish must overcome drag. There are two types of propulsion 

1. Caudal propulsion = up and down movement of tail to propel forward 

   1. Rely heavily on muscle

2. Fin propulsion (typically pelvic fin) = Use of fin when not moving 

What characteristics are viewed in undulatory vs. oscillatory swimmers?

Both utilize pectoral fins

Undalatory - More of the body is used for this; more s shaped movement 

Oscillatory - Mainly the caudal tail in use; Faster movements 

What is the equation used to predict a fish’s flow pattern?

Re = uL/V

Re = Reynolds number

u = swimming speed, m/s

L = Body length, m 

V = kinetic viscosity, m2/s - always the same

Describe friction drag vs. pressure drag

Impacted by the fishes size

friction drag - More friction drag with flatter bodies

Pressure drag - More pressure drag with wider bodies

Explain friction in relation to cost in fish

The faster a fish moves the more friction it must overcome

• energetic cost increases exponentially

• Metabolic cost is also calculated as cost over time 

Fish do not follow this and rather have a cost over distance with no minimum cost of speed 

Is locomotion the same in all fish

No, fish can have different “gaits” or pattern of movement  

What are derived characters seen in Sarcopterygians?

1. Deep water swimmers so they have a torpedo (disc shaped caudal tail) 

2. Gas bladder filled with oil - helps maintain bouyancy 

3. Ovoviviparous 

4. Intracranial joint and basicular muscle (contractions crank mouth open)

5. Rostral organ similar to the ampullae of lorezini 

6. Two nostrils 

What differences are observed in the fossil forms of aquatic to terrestrial living?

1. Eusthenopteron and Panderichthys are closely related to lungfishes - similar head structure

2. Tiktaalik- dorsal ventrally flattened head: fishlike and tetrapodlike structures 

   1. Tetrapodlike - No connection between head and pectoral girdle, no opercular bone, robust ribs and vertebrate 

3. Acanthostega and Ichthystega are zygapophores (connecting of neural spine) and have digits/limbs although their limbs probably could not bear the adult weight. 

   1. Groove cleithrum suggest internal gills 

   2. Acanthostega may have fleshy operculum 

What was needed for the transition from aquatic to terrestrial living ?

1. Ability to respire - close relation to lungfish so can already breathe air

2. Limbs or ability to move on land - some bony fish could already use their fins to move on land

3. Digits - Gene expression during fin development

   1. Hoxd13 and alx4 both expressed in fin development 

   2. Only hoxd13 expressed in hand 

What are the characteristics that Caecilians have? What taxon are they a part of? What group are they sisters to?

A part of Amphibians and are sister to batrachia.

1. Use the interhyoide muscle to close their jaw - unique to Caecilians 

2. Adductor mandibular (ancestral) - aid with closing mouth and all amphibians have this 

What are some synapomorphic characters that amphibians have?

1. Skin used for gas exchange aka cutaneous respiration 

2. Pedicellate Teeth - only oral teeth, generally homodont and polphyodont

3. Papilla amphibiorum - Laguna is not elongated and there are two organs of corti - basilar pappilar and Amphibian papilla 

4. Middle and inner ear arrangement 

5. Levator/retractor bulbs muscle function - eyes aid in swallowing food 

6. Green rods (retinas) 

Describe pedicellate teeth 

calcified crown (cusps) and calcified root (pedicel) with flexible collagen fibers in between and thin enamel on the teeth 

Describe the papilla amphibiorum in comparison to a mammals ear

Mammals have an elongated laguna and the organ of corti

Amphibians do not have an elongated laguna and they have two organs that are the organ of corti.

• basillar papilla (used for high frequencies) - seen in other saurposids

• Papilla Amphibiorum (used for low frequencies) - unique to amphibians

Describe the two pathways seen in the middle and inner ear arrangement

External ear - tympanum

Basilar Papilla - Sound causes middle ear bone (columella) to vibrate. This is connected to the stapes (connected to the inner ear) and the basilar papilla is activated. 

Papilla Amphibiorum - low vibrations move through the shoulder girdle and the operculum muscle mathway is opened and activates the papilla amphibiorum

Describe the levator/retractor bulbs muscle function

Levator = push out

Retractor = push in

No hard palette between the mouth and eyes so when amphibians swallow they blink and their eyes help push the food down

What are green rods? What is the reasoning behind this?

Green rods (retina) - second type of rod that is sensitive to light close up to the blue peak

• during low light, amphibians can still distinguish colors, specifically blue 

reason 1: lots of Amphibians have bioflourescence - compounds in the skin that absord light at one wavelength and re-emit it at a longer, visible wavelength 

reason 2: selective pressure lets other frogs see each other and allow them to live as  nocturnal creatures

Describe an amphibians diet and eating adaptations 

carnivores - mainly invertebrate 

Amphibians = large heads

Anurans

• Sticky tongue that flips forward when getting food 

Salamanders = tongue projection 

• Plethodontidae have a hyoid apparatus (a skeleton separate from the rest of the skeleton) which shoots out with tongue during projection 

• Salamanders with lungs also have tongue projection but their tongue simply slides off the skeletal rod

What type of breathing system is seen in amphibians?

Faveolar lungs - central cavity with tiny cavities going to the side

Buccal pumping - mouth is the main force that aids with filling and exhausting of air inside lungs

• Two-stroke system - expansion & compression

Describe the circulatory system in relation to breathing in amphibians

Hybrid system - so sometimes they rely on lungs and other times they don’t

Amphibians only have a divided atrium (not ventricle)

• perfect when they don’t use their lungs to breathe- helping with cutaneous respiration

• imperfect because it can cause mixing of deoxygenated and oxygenated blood 

Describe the life history of caecilians 

legless and some maternal care

intermittent organ (everted cloaca) and internal fertilization

• some oviparous and some viviparous 

Lots of toxins in skin - color blue to red give a warning 

lots of embryos have big external gills 

• live on secretion in uterus and by eating mothers skin 

Describe the life cycle of Salamanders

Internal fertilization: most lay eggs

• males drop spermatophores and females pick it up

Different courtship procedures (typically with pheremones)

Lay eggs in either aquatic or moist environments

Describe the life cycle of Anurans

External fertilization - tail frog, coqui, etc are exceptions (inverted cloaca)

• egg-laying sometimes in terrestrial environments - eggs are protected

Nuptial padding on digits are secreted on males during mating season

• These pads have glands that secrete a compound molecularly similar to pheromones to induce egg-bearing

Frogs have mating calls - vocal sac and an opening that dictates the sound made based on its size

• energetically expensive and predatory risk

Describe amphibian locomotion

Salamanders = lateral undulation

Caecilians = serpentine (like snakes) and concertina locomotion - extension of front half of body, anchoring the back half and pushing forward.

• internal concertina locomotion - Internal is primarily used for digging

• concertino locomotion - external is used in addition for climbing or just moving

Anurans = evolved to hop, jump, and climb but not all perform the same motion due to different forelimb length

Describe osmoregulation (maintaining water) in amphibians

Amphibians lose water quickly within their bodies

• anurans have a pelvic patch where they lose or gain water quickly - they sit in water to intake water

• They change shape with wet/dry nights - dry nights they hunker down 

Water-living amphibians rid of waste via ammonia 

lang-living amphibians rid of waste via urea. They can store urea in their bladder and take water out when they need it

What are “waterproof” Frogs

These are frogs that lose water at a lesser rate than typical but they can get too hot so they sweat- Chromantis and Phyllomedusa

Chromantis - Believe that the expansion of iridophores (produce tons of guanine) aids

Phyllomedusa - Glands produce a waxy secretion that they place onto itself 

What synapomorphic characters do amniotes have

1. Pentadactyl

2. Aspiration breathing

3. Necks become more prominent/distinct

4. Amniotic egg with four membranes surrounding embryo

5. More keratin in epidermis and more lipid (adipose tissue) in skin helps avoid water loss - many inaugmentary derivatives

6. Skull structure- wide flat skull w/ muscle that closes the lower jaw (aadductor mandibular)

Benefits/cost of aspiration breathing

Benefit: Less energy costly 

Cost: If the neck is too long then pushing air is much harder than pulling, so amphibians need longer necks

What makes the neck become more prominent?

The atlas and axis vertebrate are diffused to aid with neck mobility.

Describe the muscles in the skull

Different number of holes in the skulls of different lineages of amniotes

• synapsids have ONE opening 

Adductor mandibular - muscle going up towards skull 

Muscle attached to palate which allows side to side jaw movement

What structures do the adductor mandibular differentiate into?

Temporalis - close to eye (think temper) 

Masseter - Lateral (goes up) attached to upper jaw

Pterygoideus - goes sideways attached to upper jaw 

How does locomotion differ in synapsids vs. sauropsids 

Synapsids have evolved to have limbs under their body and they run in a way which aids in faster movement (quadrupedal)

• Lordosis - bending of the spine 

• diaphragm 

• Ankle bone (astragulus) that the tibia fits into. Astragalus and calcaneum are separate

Sauropsids fastest movers are bipedal (birds). Reptiles cannot move quick for long distances due to limbs 

• Complete fusion of ankle bones 

• movement of the tail aids in running

Describe the difference in lungs of synapsis and sauropsids

Ancestral lung was a cavity with pockets on the inside.

Synapsids = aveolar lung - gas exchange has a bidirectional flow

Sauropsids = faveolar lung - air flow in parabronchi and gas exchange has a unidirectional flow (More efficient) 

How does osmoregulation (elimination of waste) differ between sauropsids and synapsids?

Sauropsids and Synapsids evolved different methods of eliminating metabolic waste while minimizing water loss. 

Synapsids = primarily through urea.  

• Kidney is capable of producing concentrated urine containing urea and salts to reduce water loss

Sauropsids = Primarily uric acid. Yet this is not very soluble 

• They conserve water by concentrating uric acid until it precipitates then they eliminate it as a solid (white paste or powder is urine)

How does the circulatory system differ between sauropsids and synapsids? 

Both evolved a separation of the ventricle into the pulmonary and systemic sides with a permanent septum. Yet, this evolved differently. The amniotic ancestor lacked a ventricular septum.

Synapsids =  The ventricular septum is complete and the lower portion of the right systematic arch is lost.

Sauropsids = The left systemic arch is lost and the sinus venosus has been subsumed into the right atrium

What is ectothermy?

Energy for heat comes primarily from outside the body

Ectothermic vertebrate have a desired temperature known as a set point temperature (lives in hypothalamus)

What are some microhabitat selections that ectotherms perform for thermoregulation

• Basking

• Sun/Shade

• Amount of body exposed

• Angle Vis-a-vis sun

What is a cooling body temperature behavior that ectotherms perform? 

Panting (most do gluttural fluttering)- Not breathing, keeps the brain cool but cost water 

• Cost: Respiratory alkilation - pH of blood increases 

What factors affect desired body temperature in ectotherms?

• Activity 

• Eating - Specific dynamic activity of food or thermic affect of food = dietary induced thermogenesis

• Breeding and Pregnancy

• Infection in some (behavioral fever!) 

Types of enpoints in vertebrate

1. Heat death = complicated and not always obvious but probably due to changes in process rates (typically seen with organ failure) 

   1. Metabolic process that requires enzymes but changes don’t affect all steps equally 

2. Cold Death (Mainly in ecthotherms)= Usually simple; typically die at their freezing point 

What are strategies vertebrate use to avoid death by freezing

1. Lowering freezing points with solutes. - increase osmotic potential by accumulation of solutes in body.

2. Live in “super-cool” temperatures - living in water below their freezing point.

3. Freezing point depression with antifreeze compounds (thermal hysteresis) - Glycoproteins/small proteins help stop the growing of an ice crystal.

4. Freeze tolerant/freeze! - Increase solute concentration in cells as ice grows to stop the ice’s growth

What is the advantage and disadvantage of being eectothermic?

Advantage:

• Lower metabolic rate - they eat less

• Can be smaller, elongated, or irregularly shaped

• Less energetic cost to maintain body temp

Disadvantage: 

• Body may not be near optimal performance temperature

What are the synapomorphic characteristics seen in the taxa Squamata

1. Determined growth - growing to a specific size 

2. Ecdysis aka shedding skin

3. Hemipenes - bilateral reproductive system and cloacal opening is transverse (side to side) 

Describe locomotion seen in snakes (serpentines)

Locomotion is known as serpentine locomotion.

Part of the body push forward and they pick up other parts of the body to reduce friction (changing weight distribution). 

Describe snake eyes

1. Permanent, clear eyelid known as spectacle 

2. Accommodation occurs by moving lens back and forth (similar to aquatic vert.) 

3. Snake cones are modified rods and color seeing is derived from rods not cones 

Describe snake chemoreception

Taste: Snakes have a forked tongue used for sensation

Smell: The tips of the tongue goes on the vomeronasal/jacobsen’s organ, located on the roof of the mouth, to help with smelling

Detection: Snakes can detect heat using infrared receptors which can accommodate for poor eyesight and helps with night hunting

• two pits on the face which can help with infrared absorption  

Hearing: No external openings but an inner ear with 3 semi circular canals and a columella 

• The columella interacts with he quadrate bone that is connected to the lower jaw 

Describe snake lungs

1. Reinforced trachea

   1. One lung is highly reduced: faveolar lungs: long lung which is smooth and doesn’t have lots of faveolar pockets 

2. Glottis extends out of the mouth - snakes can breathe out of this

3. Lung acts as bellows - aids with sucking in large prey and blocking air 

Name and describe the three snakes taxas we’ve learned in class

1. Thread and Blind Snakes - small, no fangs.

2. Pythons and Boas - Constrictors, no fangs.

3. Vipers, elapids, and colubrids - venom and fangs (teeth modified to deliver venom). Many colubrids don’t have fangs but can still produce venom in their saliva

Describe the traits for vipers, elapids, and colubrids

Vipers

• Solenglyphous = hollow, folded fangs

• Teeth on maxilla, hinge action, and deliver venom most rapidly

Elapids 

• Proteroglyphous = permanently erect fangs, fangs form needle, hollow bit

• Most venomous of all snakes 

Colubrids

• Opisthoglyphous = rear fanged

• Weak venom grooves in teeth to deliver venom