Fishes and Amphibians Flashcards
Living my jawless fishes are known as …
And include what species?
Cylcostomata
(Round mouth)
Hagfish
Lampreys
What is a fish?
Aquatic vertebrate will gills, appendages in the form of fins (if present), and usually the skin is covered in scales
Fish vs fishes
Fish refers to one or more individuals of a species
Fishes refers to more than one species
What species with fish like names are not actually fish
Jellyfish, starfish, crayfish, shellfish
Specific challenges of aquatic environment
-water is 800 times denser than air
-most fished adjust to salt and water balance of environment
-gills extract oxygen from water (water has 1/20th of the oxygen in air)
Clade Cyclostomata specific adaptations for hagfishes and lampreys
Hagfish: knot tying and slime
Lamprey: parasitism, best building
When did Cyclostomata appear
Ancient fishes that hbu exchanged little over 400-450 my
External characterisitcs of jawless living fish
-body is slender and eel like
-skin naked (no scales)
-caudal fin
-pore-like hill openitna
-distinct head: tripartite Brian encoded in cartilaginous skull
What do jawless fish not have?
Jaws, paired nostrils, paired fins, mineralized tissues (bone, teeth)
Hagfish and lamprey internal characteristics
-adults have notochord
-rudimentary vertebral elements (cartilage)
-pharyngeal muscles power gills for respiration
-keratinized “teeth” structures on tongue or oral hood (lamprey): not real teeth
Nostril in hagfishes and lamprey
Nasohypophyseal opening
One nostril that contains olfactory epithelium to smell. The opening for the nostril connects to the pharynx, so that hagfishes CNS breathe through their nostril!!!
In lampreys too( but does not connect to pharynx so lampreys cannot breathe through nostril
Posterior to the nasal sac in hagfishes is the ______
Adenohypophysis (anterior pituitary)
Barbel
Whisker like sensory organ in hagfish
Lamprey features not present in hagfish
Dorsal fun
Eyes are more developed in lamprey (pineal eye)
Habitat of Hagfish
Marine, worldwide
Deep water
What are hagfishes overfished for
Eel leather or food
Hagfish feeding
Scavengers: large numbers of hagfish are quickly attracted to the smell of dead or dying fishes or other animals (whales), enter body of animal.
Use keratinized “teeth” on tongue to rasp bits of flesh from prey
Tie into knot
How do hagfish escape capture
- Tie themselves in knots for leverage to heal press or escape
- Slime!!!! To choke prey. Scrape off with knot after (produces from muscles glands)
Hagfish slime parts
-70-200 slime glands secrete mucin (mucous) and protein threads, each contained in separate cells
-when they contact water, Mucin absorbs water and threads unfurl to bind mucin into continuous mass of slime
How do hagfish reproduce
-not much known: don’t reproduce in captivity
-females outnumber 100 to 1, some are heterotrophic
-females produce yolky eggs that attach to the bottom of sea
-eggs take 5 months to hatch into hagfish: no larval stage
Latin name for lampreys means what?
Rock licker
Petromyzontiformes
Lifestyle of lampreys
Anadromous
Live as adults in oceans or large lakes, ascend rivers and streams to breed, then die
Lamprey feeding
Most are parasitic (adults)
-use suction of oral hood to attach to host
-sharp keratinized teeth and rasping tongue drill hole
-oral gland secretes anticoagulant
-don’t kill host, but leave weakened
How do lamprey respirate
Flow through ventilation: applies to larva and adult not attached to prey: draws water into mouth and pumps out through gills
Tidal ventilation: when attached to host, acquire oxygen by moving water in and out of gills
Characteristics of non-parasitic lamprey
-small (<20cm)
-inhabit small streams
-poorly developed teeth
-brief adult period (<6 months)
-don’t feed as adults
-spawn, then die
Northern Brook lamprey
3 Manitoba species of lamprey
-chestnut (parasitic)
-silver (parasitic)
Both above about 35cm
-northern brook (non parasitic)
Lamprey nest building and spawning
-male begins building nest, and is joined by the female
-use oral hood to life rocks, and vibrations to remove debris
-female lays eggs and male fertilize
-monogamous
-die after spawning
How do male Lamprey attract females and mate with them
-Male dorsal adipose ridge tissue that heats up 0.3° when female is present: Rope tissue
-pheromone to attract females to area
-Thermogenic secondary sex characterisitc
-males rub rope tissue over females abdomen and if she agrees she will rub her Urogenital pore against the tissue in return.
-male then wraps around her tightly, bites onto her head and locks into her by tying a knot with tail.
-both release sex cells together and fall into nest
Lamprey life cycle steps
- Large number of small eggs hatch, larvae leave nest at 1cm long and burrow into sand (Ammocoetes)
- Ammocoetes live sedentary in fresh water burrows and filter feed for 3-7 years
- Metamorphosis: over two months, become parasitic
- Parasitic growing stage: emerge as small (13cm) adults. Lasts 1-3 years and they feed on large fish
- Reproduce and die in streams
Sea lamprey effect on Great Lakes
-originally only in eastern lakes, but human made canals connected them to all 5 of the great lakes
-negative effect on native fish species starting 1930 and still today
-Trout population diminished
Sea lamprey control methods
Larvacides: chemicals to reduce larvae in spawning streams
Possibility of using pheromones to attract females away from males or trap them
Most modern day fish, except the lampreys and hagfish are part of the Clade called _________
Gnathostomata
Jawed vertebrates
Conodonts
Soft-bodied animal with mineralized teeth (high proportion of hydroxyapatite, which gives harness to teeth)
Extinct jawless fishes
When were conodonts around
300mya
Ostracoderms characteristics
Groups of jawless fish
-Dermal armours (exoskeleton) in form of large plates that cover head and sometimes the pectoral region or covered a portion of the body
-jawless
-more derived forms had paired pectoral fins (no paired pelvic fins)
Ostracoderms time period
-orodovician (period followed the Cambrian until end of the Devonian)
Mass extinction at end of Devonian wiped them out
Placoderms
-plate like dermal armour covering the front 1/3 to half of the body
-paired pelvic and paired pectoral fins
-lower jaw resembles jawed vertebrates
-inner ear with 3 semicircular canals
-external organs (clasper)
-presence of an external reproductive organ (internal fertilization)
Example species of Placoderms
DUNK
Are placoderms true Gnathostomes
Yes - bones forming upper had are homologous to bones in gnathostome jaw
When did placoderms go extinct
End of Devonian in mass extinction
Evolution of the jaw
- Basal gnathostomes: placoderms. Lower jaw resembles gnathostomes
- More derived placoderms: have a maxilla and pre maxilla bones in upper jaw
- Cartilaginous fishes (lost bony skull)
- Crown gnathostomes: include ray-finned and lobe-finned fish (includes tetrapods)-retain bony skull and these are refined
Phylogeny of early vertebrates
- Cyclostomata: lamprey and hagfishes: evolutionary oldest extant vertebrates
- Conodonts: jawless, with mineralized teeth, long fossil record into Mesozoic
- Ostracoderms: jawless, abundant; extinct by end of Devonian
- Placoderms: jaws, abundant until end of Devonian
Advantages of paired fins
-thrust, steering and stability in three dimensions
-tail fin-> primary thrust
-Anal and dorsal fins->lessen rotation or side to side swing
-pectoral and pelvic -> control vertical tilt; act as brakes, occasional thrust
Dermal bone
Ossification of cells of skin with no cartilaginous precursor
-forms exoskeleton
-head shield or scales of ostracoderms
-most of our skull plates
Endochondral bone
-Begins as cartilage, then ossifies
-forms Endoskeleton
-vertebrae of bony fish and tetrapods
-fin or limb bones in fish or tetrapods
Are fin rays dermal or Endochondral
Dermal
Jaws enabled what?
Active foraging
Supported higher levels of activity
Predators to capture prey that are larger than themselves
Upper and lower jaws develop from _____
Hyoid develops from
Pharyngeal arch (Mandibular arch)
2nd arch (hyoid arch) and helps brace jaws
Jaws and nostril development in Cyclostomes and Gnathostomes
Single nasohypophyseal placode blocks migration of Mandibular tissue around mouth
-one opening and placode for nose and anterior pituitary
Separation between 2 nasal palcodes and hypophyseal placode
-gives room for Mandibular cells to migrate and form upper jaw
The fossil record supports the hypothesis that jaws cannot develop until ……
Two nostril have formed with a separation in the location of the anterior pituitary
Need 2 nasal openings and separated anterior pituitary
Why did jaws arise
- Enable animals to prey on large and active animals
- Improved ventilation- changes in Mandibular arch made it possible for fish to close their mouths. Closure of the mouth may have been an early step in creating a “double-pump” system of hill ventilation still used in jawed fishes today.
Chondrichthyes
Cartilaginous fishes
-ancient group appearing before Devonian
-living forms are highly derived
-about 1200 extant species in 2 lineages
2 lineages of Chondrichthyes
Elasmobranchii: sharks, skates, rays
Holocephali: chimeras
Elasmobranchii skeleton, and teeth, and body covering
-cartilaginous skeletons with crystalline calcium including the skull: chondrocranium
-loss of dermal bone:
-teeth and placoid scales: thick tough mineralized scales known as placoid scales or dermal denticles. Teeth evolved from the dermal placoid scales
Elasmobranchii respiration
Gills to absorb oxygen from the water
-5 full slits on both sides of the body
-spiracle: water pumped into small hole behind eye as another way for water to enter body.
Elasmobranchii and an _______ mouth
What helps Elasmobranchii locomotion
-fusiform shape: streamline body and placoid scales reduce drag
-heterocercal tail: vertebral column extends into dorsal lobe of tail
-enormous oily bodies in liver reduce density as sharks otherwise sink due to heavy body and no gas bladder
How do Elasmobranchii deal with their loss of teeth
Teeth replacement
-Polyphyodont: continual teeth replacement.
-sharks replace teeth every 8 days
-Tooth whorl: conveyer belt of new teeth ready to go behind current teeth
Jaw suspension and profusion of Elasmobranchii
-hyostalic jaw suspension: derived form of jaw suspension in which the upper jaw moves independently of the cranium
Advantage: animal expands and protrudes jaw giving it ability to catch larger prey
Gaelomorphii shark: Whale shark
-up to 19m in length: largest non-mammalian vertebrate
-mostly filter feeder of Plankton
-
Galeomorphi shark: Hammerhead Shark
-distinct head serve to enhance directional sensitivity of neuromasts (lateral line) and electro receptors in ampullae or olfaction
-grow more than 6M
Gaelomorphii sharks: walking sharks
-walk around on sea floor bottom on search of small crustaceans or fish
Squalomorphii sharks: Greenland shark
-longest life expectancy of vertebrates at 392 years
-reach sexual maturity at 150 years
-can grow larger than 6.5m
-slow swimmer with presumed slow metabolic rate
Squalomorphii shark: cookie cutter shark
-<50cm long
-deep water
-feeds by biting pieces of flesh of sharks, tuna and dolphins
_____% of Elasmobranchii are….
Skates and rays
Habitat and body form of rays and skates
-sea floor life
-dorsal-ventral flattened body: enlarged pectoral fins for locomotion
-mouth and gills on ventral side, spiracle on dorsal side
-flattened teeth for crushing crustaceans, molluscs and echinoderms
Skates vs rays
Skates:
-rounder body
-long, thick tail with two dorsal fins and one caudal fin
-oviparous (egg laying)
Rays:
-kite body shape
-thin, whip lash like tail
-fins replaced by enlarged serrated, venomous barbs
-viviparous
Holocephalli: the chimeras unique traits
-live in deep water
-dense concentration of mechano and electro receptors on head and rostrum to detect prey
-3 pairs of continuous growing flat tooth plates
-mixed diet of crustaceans, echinoderms and fishes
How is sound different in water than air
Travels 4x faster
Two senses highly effective in water but not air
-Mechanoreceptors: water is more dense than air so movements make currents and can then be perceived. Lateral line helps detect these
-Electroreception: water is a good conductor of electricity.
Mechanoreceptors
-Touch, pressure, motion and sound detector
-include the lateral line and inner ear
Lateral line and inner ear rely on what sensory unit?
Sterocillia within hair cells
Mechanoreceptors within sensory hair cells detect movement of fluid resulting from motion in water external to the animal or from a change in the body’s position
Not actually made of hair!!! They are cilia
What does the vestibular apparatus of inner ear do in sharks?
Detects movement of fluid in the ear caused by own body’s movement
-semi-circular canals: 3 canals arranged at right angles, which detect motion of the head in any direction
-otolith organs (sacculus and utricle): detect linear acceleration
Shark hearing
-sound passes through body to sensory “hair cells” in inner ear
-hear frequencies of 10-800hz (low frequency
Lateral line system
Series of canals over the head and along the body, with water entering through surface pores to contact neuromast organs
-neuromasts have clusters of Mechanoreceptors in “hair cells” that detect water movement and low frequency vibrations and transmit them to nerve cells
-localize prey and predators
Electroreception
-shark and ray heads and pectoral fins of rays have electroreceptors (ampullae of Lorenzini) that detect bio electric fields of animals
-modified lateral line system
-gel-filled canal conducting electricity from surface pore to ampullae receptor) , which is attached to nerve
Shark eye adaptation to aquatic environment and low light light conditions
-aquatic: spherical lens focuses image on retina: muscle moves lens towards or away from retina
-low light:
-high concentration of rods, photoreceptors
-tapetum lucidium: reflective layer behind the retina that enables light to bounce off retina a 2nd time so more photons can be absorbed
Shark sensory structures for short, middle and long distances
Short <20cm: electroreception
Middle: vision and sound
Long >700cm: Olfaction, Mechanoreceptors: turbulence and low frequency vibrations
2 characteristics of sharks, rays and skates reproduction
- Dioecious-separate male and female individuals, or hermaphrodite capable of being female or male but are not typical.
- Internal fertilization: claspers: sperm transfer
Oviparity
40% of sharks and all skates
-large eggs in protective cases
-nourished by yolk sac
-no parental care
-young “fully formed”
Higher fecundity-larger offspring numbers compared to viviparous sharks
A gland at the end of the mothers oviduct secretes:
A proteinaceous case around egg and it hardens after a few hours in contact with sea water
Have tendrils to help egg stay in position in crevices or vegetation
Organic waste flushed out of case through small opening; water and oxygen enters
An egg case surrounds a ______ and ____
Single embryo
Yolk sac
Distinct in different species
Viviparity
-many sharks (60%) and all rays
-embryo retained in reproductive tract
-more common in larger species which have larger young
-gestation can take 1-2 years
-uterus protects embryos from predation
-no parental care after birth
Two types of viviparity
Ovo-viviparity: yolk sac or aplacental viviparity
-mother gives birth to live young, but embryos rely entirely on yolk sac for nutrition until birth
Matrotrophy or placental viviparity: mother supplies energy to embryo, for example: protein rich uterine secretions, placental connection so offspring receives nutrients from mothers blood, consumes additional resources produced by mother (eggs, siblings)
Combination: embryos of many species obtain energy from both sources
Siblicide before birth in tiger sharks
-Females mate with multiple males to produce embryos with different fathers
-multiple embryos develop in each of 2 uteri
-first and largest embryo consumes siblings of other eggs in each uterus
Possible competition between males to father young after fertilization
Reproductive specialization in sharks and rays
- Internal fertilization ensures no gametes float away
2.invest heavily into young at stage of egg production and when carrying the embryo or egg before birth
3.no larval stage - Parental care ends at birth
- Produce fewer offspring at one time, but offspring have high survival
Life history characteristic’s
-offspring per reproductive episode (fecundity)
-number of reproductive episodes
-age of maturity
-duration of life span
Fast vs slow life history
Fast: small snails that develop quickly, produce large number of eggs and has a short life
Slow: large animal that takes years to mature, produce small number of offspring, has few reproductive episodes and has a long life span
Sharks have what type of life history
Slow
Slow life history connection with conservation
Slow life history especially low reproductive rate means that a population will have trouble recovering once it is reduced in numbers
Exploitation of sharks
-100m killed by humans years year, mostly for the fins
-also killed for meat (fish and chips), cartilage or as by-catch
Shark finning
Traditional and most common practice is to cut fins, then discard animal into the ocean
-inhumane
-ecological consequence of removing a top predator
Canada and shark finning
Banned in 1994, but imports are allowed
Banned imports of shark fins in 2019
What is helping sharks in conservation
-Banning finning and imports of fins
-shark ecotourism brings in a ton of money and expected to grow more! Therefore making them worth more alive.
Osteichtyes meaning
Jawed fishes
All major lineages of fishes, extant and extinct, coexisted during what time period
Devonian (419-359mya)
-jawless
-jawed
-jawed and bony
Two extant groups of bony fishes
Sarcopterygii-lobe finned fishes
Actinopterygii-rated finned fishes (include teleost with 98% of modern fishes
Bony fishes compared to cartilaginous fishes have what characteristics?
-bony fishes coming in fresh and marine water
-usually bilaterally flattened
-enodondral bone
-scales are softer or smoother
-no spiracle
-external fertilization (usually)
-larger number of eggs
Key characteristics of bony fishes
- Fully ossified skeleton (vertebrae and appendages) made of Endochondral bone
- Dermal bone surrounds braincase
- Dermal jaw bones bear teeth
- Operculum over gills increases respiratory efficiency
- Gas bladder
Operculum helping respiratory efficiency
- Operculum closed, mouth opens to draw water in
- Outward movement of operculum created negative pressure (suction) that draws water across the gills, and out
- Oxygen absorbed through gills into bloodstream (countercurrent flow)
Some fish able to extract 85% of oxygen from water
Gill raker function
Strain out food and debris
Ram ventilation
Fishes like sharks that rely on swimming forward and constant motion to force water through the open mouth and across gills
Operculum ventilation prevents this
Gas bladder for respiration, buoyancy or both
-adjust volume of gas to achieve neutral buoyancy
Ascend: let gas out of bladder
Descend: mechanisms to move oxygen from blood vessels to gas bladder
Started as out-pocket of gut or esophagus
Lobe finned fishes ancestral and modern trait comparison
-early forms had lungs and gills; modern have lungs except coelocanth
-ancestral forms had fleshy, strong paired fins
-ancestral forms had heterocercal tails; living forms have diphycercal tails
When were lobe finned fishes most diverse
Devonian
Tail variation
-heterocercal: extant sharks, extinct lobe finned fish
-diphycercal: extant love finned fish
-homocercal: ray finned fish
Australian lungfish
Most similar species to ancestral lobe-fins: lobe-like fins and thicker scales than other lungfishes
-water breathing: rely on gills for oxygen
-lungs supplement gills during times of stress
-obligate air-breathers: drown without
-burrow in mud during dry season, secrete mucus to mix with mud to form hard cocoon.
-dormancy for up to 4 years
-reduced fins, but can still move ok land or underwater, using pelvic pins to lift body
Coelocanth
-first known giant form from early Devonian
-thought to be extinct till 1938
-large:75cm to 2m long
-viviparous
-usually 250-300m deep
-rely on gills for respiration
-have a lung filled with fat as hydrostatic organ
Extant sister group to tetrapods
Lungfish
Tetrapodomorph
Important group of Sarcoptrrygii fish that have some characteristics also found in tetrapods. Includes Eusthenopteron and Tiktaalik
-choanae: internal nostrils that conenct external nostrils to pharynx
-bones homologous to tetrapods in arms
-dorsal-ventral flattened heads with nostril on dorsal surface in some like tetrapods
Tetramorph fishes were extinct by the _______
Early Permian
Actinopterygii 2 groups
- Relic groups- sturgeon, bichirs, bowfins: Cladistia and Chondrostei
- Air-breathing fishes
Cladistia chatacterisitcs
Bichirs and reedfishes
-freshwater fish from Africa
-many “finlets” on dorsal surface
-armoured with ganoid scales (thick, diamond shape, interlocking)
-come to surface to gulp air; have lungs
Chondrostei characteristics
Sturgeon and paddlefishes
-anadromous or freshwater, NH
-primarily cartilaginous skeleton
-dermal scutes (Armor-like scales) on back
-certain similarities to teleosts evolved independently: swim bladder, no lung, jaw not fused to cranium
Sturgeons
-Largest freshwater fish
-benthic (bottom) cruiser
-highly protrusile mouth oriented downward, suction feeder (no terrh$
Sturgeon life history
- Large size, slow growth, long life
- Mature 15-25years
-lifespan 50-80 years
-high fecundity and small eggs
-spawn in rivers, no parental care
Sturgeon conservation
- Overfishing since 1880-1900’s
-have not recovered and still poached - Hydropower dams alter habitats and interior travel corridors and impact egg survival and larvae
The Devonian had which fish groups
Ostracoderms, placoderms, Chondricthyes, sarcopterugians, and actinopergii (ray finned fishes)
Teleosts
-how many species
-habitat
> 30,000 species - making up 96% of all livi mg fish species
Worldwide, in all aquatic habitats
Earliest repository fossil
When did Euteleosts appear
First tee lost appeared when
From the Triassic (Mesozoic)
100mya
200mya
Basic trends in the ray-finned fishes and teleosts
- Heavy dermal armour replaced by light, thin flexible cycloid and ctenoid scales, allowing for increased mobility
- Homocercal tail allowing greater speed and buoyancy
- Swim bladder shifted from primarily respiratory to buoyancy in function
- Fins changed to provide greater mobility and to serve a variety of functions: braking, streamlining, social communication, camouflage, protection. Pectoral find moved to dorsal, pelvic fins moved more anterior.
- The use changed to enable increase suctioning and jaw protrusion to obtain food
The larger the fish, the ______ they swim
Fast swimming species are _____ flexible
Faster
Less and limit undulation to caudal region
How do swim ballers increase hearing sensitivity
-swim bladder amplified sound, increases hearing range (frequency) and amplitude. Teleosts can hear more than sharks or rays.
-some teleost groups improve sensitivity with a physical connection that conducts sounds directly from the swim bladder to the inner ear
Ostariophysi and hearing
Catfishes, carps, minnows and more
-80% fresh water species, 25-30% of all fishes
-small bones (weberian ossicles, modified vertebral elements) transmit sound form swim bladder to ear.
Enables them to heat up to 4000hz, sharks can only heat up to 1000hz
Swim bladder vs lungs of fishes
Swim bladder:
-primarily function in buoyancy
-enhanced hearing, especially when physically connected to inner ear
-may function in respiration in a small number of fishes
Lungs:
-primarily function in respiration
-have more surface area and are more vascularized (more blood supply)
-lungs appeared in fishes long before tetrapods invaded land
-secondary functions: buoyancy, possible hearing
Swim bladders and neutral buoyancy
-Swim bladder is the most efficient flotation device. Neutral buoyancy means that find do not have to provide lift.
-mechanisms to adjust volume of gas entering or leaving bladder as fish moved up or down to maintain neutral buoyancy.
-greater pressure at depth reduced volume of gas in bladder; obtain more oxygen from blood via gas gland
-as ascending, has expands so expel gas from bladder (either to gut or to blood then gills)
_________ is extremely well developed in teleosts
Jaw protrusion: mobility of upper jaw elements (premaxilla and maxilla) that border mouth enables jaw margins to extend forward.
Membrane of skin closed gap, increased effectiveness of suction and prey capture
Similar to sharks, teleosts have developed the ability to move the ______________ independently of the mouth so as to protrude their jaws forward
Upper jaw
Suction feeding
Rapid expansion of pro tan hail cavity (mouth and gill) creates negative pressure, drawing in water and prey
Enabled by jaw protustion
Freshwater drum teeth
-incisor like anterior teeth on dentary for nipping prey off substrates
-pharyngeal teeth for shredding prey or crushing mollusk shells: shaped like rounded molars.
Most teleosts have _____ sets of jaws
2 sets
Oral jaws used to capture and manipulate prey
Pharyngeal jaws at back of the throat to process food and love it from the mouth to the stomach
Moray eels jaws
Mooray eels extend pharyngeal jaws into the oral cavity to grasp prey struggling in the eels mouth
Temperature regulation and endothermy in fish
-body heat rapidly lost to water, especially with water running over blood vessels in the gills
-most fished have body temperature similar to water temperature. They depend on the external environment to regulate their temperature (ectothermy)
Some large marine species keep certain body areas warmer than water: swimming muscles, visceral organs like the heart, brain and eyes: blue finned tuna, mackerel sharks, mackerels = regional heterothermy
How do bluefin tuna keep their swimming muscles warm?
Elaborate network of small blood vessels called retia in the swimming muscles, close to the vertebrae. Muscular activity wants the red muscle and the retia retains the heat in that location, so that it does not disperse to more distal parts of the body.
Keep muscles 12° warmer
Retia is example of counter current heat exchanger mechanism that conducts heat from vessels carrying blood leaving the muscle to vessels carrying blood to the muscles
Why regional heterothermy?
Warmer body temperatures enhances swimming speed, sustained performance, nervous system activity
Whole body endothermy
The Opah or mood shaped fish has whole body endothermy. Mains stable body temperature as it moved from waters surface to deep, cold waters. It uses pectoral find to propel itself and these muscles produce heat, and the muscles insulate the heat by a layer of fat that is 1cm thick.
Has retia inside the hill arches that isolate the respiratory surfaces of gills from the rest of the body, which reduced the loss of heat that normally happens when water flows over the gills.
Most common developmental type in teleosts
What life history
Oviparous (97%)
-larval stage with young carrying yolk sac
R-selected life history
Variation within teleosts of egg laying
- Marine eggs in the open ocean (pelagic)
-smaller eggs, that are buoyant and released into open ocean (broadcast spawning) - Marine: near shore and benthic species lay sticky eggs that adhere to weed or gravel on the sea bed
- Freshwater species: more likely to deposit eggs that are larger and are attached to weeds or stones. Some are laid in nests or brooded. Non-floating eggs are better suited to freshwater to avoid drifting downstream. Parental care more common this way too.
Teleost development
-short incubation period followed by larval stage with young incompletely developed and carrying yolks sac
-metamorphosis: contrasts with cartilaginous fishes with no larval stage
Catadromous bs anadromous life cycle
Which are eels
Spends most of its time in freshwater and migrate to sea to spawn (eels)
Spends most time in ocean and migrate to fresh water to spawn
Eel stages
Leaf shaped eel larvae are borne at sea and in depths of the ocean. They slowly increase in size until metamorphosing into a transparent, glassy form called glass eel, which usually occurs as they start to migrate back to freshwater. The glass eel develops pigmentation and is then known as the elver.
Larvae in ocean for <1 year, in freshwater for 6-10 years
Sexual fate is ______ in teleosts, and is influenced by _______ and _____\
Plastic- only 10% of fish have sex choir moms similar to humans (XX XY). Have autosomes that can influence phenotypic sex.
Genes and environmental and social conditions
Sex determination of teleosts
-environmental factors
- Temperature: high temps produce physiological males from genetic females
- Pollutants: Endocrine disrupters influence physiological processes that affect development of gonads and sexual phenotype. - estrogen in lake feminized genetic males, resulting in decline in populations.
Many fish can switch sex during the embryonic stage
Hermaphodites
Synchronous hermaphroditism
Presence of male and female organs on same individual
Male and female reproductive parts mature together (Tripod fish)
-self-fertilization does not occur
-potential of fertilizing two batches of eggs when encountering a mate
Sequential hermaphroditism and types
Individual is either male or female early in life with potential to change to female or male later in life (physically, behaviourally and even neurologically)
Female first: Protogyny
Male first: Protandry
Protogyny example and benefit
-blue head wrasse
Fish reproduce in the open ocean as broadcast spawners. So both males and females eject eggs and sperm into ocean. A dominant male defends mating territory and mates with 40-100 females a day. if dominant blue headed male dies, either a small male or female will grow and change colour to replace it. It can take only a week.
Males in open ocean habitat benefit more by being large
Protandy example and benefit
Anemone-fish (clown fish)
Live in ocean ocean but spend lives in corals and live close to sessile invertebrate animals called anemone where they deposit and fertilize their eggs. They are monogamous. Male tends to eggs while larger female monitors and defends territory. If female dies, breeding male grows and develops female gonads to replace the breeding female. An immature fish will then develop into a mature male and partner with the female.
One male, regardless of size has plenty of Speke to fertilize the eggs of one female, so there is no advantage to being a large male. But larger female can produce more eggs than small female.
Parental care of fishes
What is typical of pelagic and freshwater fish
Pelagic-no parental care for broadcast spawning
Care more common in fresh water fishes or fishes living near shore
What percent of fishes have parental care?
What sex typically does parental care
30% of 500 fish families
Male care: 50%
Female care: 30%
Biparental care: 20%
______ most likely to care when fertilization is external
______ most likely to care when fertilization is internal
Males
Females
Forms of fish parental care
-Aerating and cleaning eggs
-Brooding (carrying eggs or young in mouth of pouches)
-post-hatching care (defence and food)
Stickleback males care
Males build nest with dome and tunnel. Court females with dance. If successful, female lays eggs in tunnel, male then chases her away and other males away. Guards and aerate eggs (7-8 days). Protects and keep hound together after hatching (3 days)
One exception to males caring for young with internal fertilization
-Make sea horses carry eggs and larval young in brood pouch or on abdomen or tail.
-expel larval young after 2-4 weeks.
Tetrapods
Vertebrates having four limbs or descending from vertebrates having four limbs (snakes, whales birds)
-includes amphibians and amniotes
Tetrapods needed support against gravity and increased location on, resulting in a _______
Skeleton-relatively rigid band strong
Skeletons and muscles of limbs and feet modified to push against substrate (ground)
Forelimb of acanthostega
-humerus, radius and ulna, carpels (wrist bones), and phalanges
-8 digits
Hind limbs did not articulate with the pelvis
Icthyostega adaptations to life on land not seen in acanthostega
-limbs were fully formed including a pelvis articulated with the vertebral column and it’s vertebral column was more robust.
-stronger backbone
-shoulder and hip girdles
-muscles support body in air, and muscles to raise head
-ear structure modified to detect airborne sounds
Forelimb with humerus, radius and ulna, carpels and phalanges
Hindlimb with genus, tibia and fibula, tarsal (ankle bones) and phalanges.
Eusthenopteron (385 mya) homologous bones to terrapods
Tiktaalik (375mya) homologous strucures to tetrapods
-Humerus, radius and ulna
-could probably use “walking” find to pull itself along substrate
-had lungs
-intermediate between lobe-finned fishes and terrapods
-probably my used limbs to support body while placing snout above water to breathe air in shallow water
Double circulation system
Who has it?
-made possible by separation of right and left chambers of atrium and ventricle that separate oxygen-rich and oxygen-poor blood
Adult amphibians have incomplete separation of chambers. There is a permanently divided atrium but the centuries are temporarily separated.
True separation for turtles and most lizards.
Mammals and birds have permanently divided structures
Applies to all terrapods (amphibians and amniotes)
Double circulation system pathways
Blood passes through the heart twice, for there are two distinct routes of circulation
- Pulmonary circulation: deoxygenated blood is pumped from heart to lungs; oxygenated blood results to the heart.
- Systemic circulation: oxygenated blood is pumped from the heart around the body. Blood returns to the heart as deoxygenated.
Fish have what type of circulation
Single circuit
Blood passes through the heart only once during full route around the body
Deoxygenated blood is oxygenated as it passes through the gill capillaries
Limitations of single circuit system
Blood flow and pressure falls when blood leaves a fish’s gills
Works for fish, but would not work on land
Advantages of double circuit circulatory system
-chambers separate oxygen rich form oxygen poor blood-> ensures blood is rich in oxygen when reaching tissues, muscles and organs
-blood is pressurized twice for each cycle around blood system-> higher blood pressure and increased rate of blood flow.
Allows blood to be pumped against gravity, enables larger body size, and higher blood flow needed for higher metabolic rates and endothermy.
Modifications to respiration in tetrapods
Modifications to lungs to increase surface area and vascularization (capillary network)
Internal nares (choanae) connect to pharynx to enable animal to love air from nares to lungs for respiration
Olfaction in tetrapods vs fish
Nasal cavity lined with olfactory epithelium that contains olfactory receptors. With each breath, air can pass over olfactory epithelium.
Have a pouch with olfactory epithelium. Water enters and flowed over this surface then exits. Fish smell after water enters pouch and contacts olfactory epithelium. With few exceptions, nostrils of fish do not connect to the mouth or Pharynx.
Lateral line system transition to land
Aquatic vertebrates have a lateral line system (fishes, larval and permanently aquatic amphibians)
-movement of water molecules directly stimulates the hair cells of the lateral line system
-amphibians lose the lateral line system after metamorphosis
-air is not dense enough to transmit information form motion or sound
Hearing in water vs terrestrial
Density of animal tissue is similar to water
Sound readily passes through animal tissues, stimulating hair cells of inner ear.
Air is not dense enough for transmission of sound or motion. Not lateral line system in terrestrial animals.
Hearing in terrestrial animals requires a ________
Middle ear: tympanic membrane (ear drum) and stapes (columella bone) amplify and transmit vibrations to inner ear, which discriminates frequency (pitch) and intensity (amplitude)
Vision land adaptations
- light transmits with less disturbances in air than in water, so is more effective for distance perception
-cornea focuses light on retina
-tetrapod lens is flexible and becomes more rounded to focus on closer objects
-eyelids and lacrimal gland protects and wash eyes which is necessary since eye has contact with air rather than water
Nictitating eyelid
Transparent eyelid to protect and lubricate eye, enabling vision found in terrestrial animals, sharks
Readily viable in amphibians, reptiles and birds
Parietal eye or pineal eye
-photoreceptive organ associated with pineal gland. Important in regulating day/night or seasonal cycles through release of melatonin. Role in thermoregulation for animals that rely on ectothermic temperature regulation
-some fishes have this too like lamprey
-mammals do not have parietal eye but do have pineal gland
Sensory disadvantages and advantages on air
Dis-air not dense enough to easily stimulate mechanical receptors or conduct electricity
Ad-air has increased light for vision
