unit 2 Flashcards
Living in water poses some challenges
- Obtaining oxygen
- Adjusting buoyancy
- Maintain body temperature
- Maintenance of a stable internal environment (due to movement of water & ions)
Most aquatic vertebrates exchange1 _______ and 2 ________ from the body via 3____
- O2
- CO2
- gills
how do amphibians exchange gasses
through their skin
Gills of teleosts are
-found in opercular cavity
-covered by operculum to prevent backflow
-unidirectional waterflow
gills project off of
gill arch
Gas exchange occurs on the ____ ____
secondary lamellae
Two ways fish are able to ventilate
- Buccal pumping: mouth & opercular
cavities pump water across the gills due to positive pressure produced (gulp water, close mouth, pump water over gills) - Ram ventilation: fish swims with their
mouth open to pass water across the gills
• Many pelagic & filter feeding fish do this
• Others may switch when actively swimming
Ram ventiliation
Passage of water _____ movement of
blood: ______ ______
opposes
counter current excahange
Most fishes use ____ to extract O2 from water
Gills
what is a labyrinth
-vascularized chamber at the rear of the head
-used to exchange oxygen and CO2 after gulping air
Bony fish - buoancy
neutrally buoyant due to well developed swim bladers
what is a physostomous fish
-have a gas bladder and pneumatic duct
-gulp air to push it to gas bladder to float more
-release air to sink more
what is a physoclistous fish
-fish with vascularized gas bladder
-have a rete mirabile (wonderful net)
-gas can diffuse across the membrane
counter current exchange
-literally means “bellows closed”
Cartilaginous fish - buoyancy
High oil content in liver
– do not have swim bladders
Deep-sea fishes- buoyancy
use lipids in a gas
bladder or through the body
refractive index of water is _____ than air
greater
lens in fishes
-refract more than terrestrial eyes
-make it possible to see in water
sound travels ______ in water than air
faster
(wavelength of given frequency is 4x longer in water)
Chemosensation
used to detect food, migration, etc
mechanorecptors detect ______ through water displacment
sense touch, pressure,
sound & motion
example of mechanoreceptors
lateral line to detect movement or vibration
Found in fish, larval amphibians & adult aquatic salamanders
electricity in water
water conducts elec –> orgs produce ele discharge –> used to detect preds, courtship or territory defence
Other organisms have
electroreception
Sharks respond to small changes of the electric field via ampullae of Lorenzini
shark food detection experiment
sharks prefer electical over chemical (smell) signal to find food
Class Chondrichthyes two groups
Elasmobranchii: elasma = plate & branchia = gills
– Between 5 and 7 gill openings on each side of the head
• Includes extant sharks, skates & rays
• Hyostylic upper jaw suspension- upper jaw not fused to the chondrocranium, permits it to be projected and retracted (SUUUUCK)
- Holocephali holo = whole; cephalo = head
– Includes ratfishes/chimaerans
– Single gill opening
– Holostylic upper jaw suspension- upper jaw fused to the chondrocranium
Class Chondrichthyes: common Charecterisitcs
- Placoid scales
– Composed of dentine and enamel with a pulp cavity
-tooth like structure
-also called denticle
-reduce friction as they move through the water
-rough and tough
-grow more scales as they grow in size (the scales do not get larger) - Cartilaginous skeleton
* Ancestral condition of vertebrates
* Mineralized with hydroxyapatite. Bone from
osteichthyans are also mineralized with
hydroxyapatite but deposited differently.
* Not necessarily weaker than bone
* More buoyant than bone
-more flexible - Teeth whorls of sharks
* dentine, enameloid & traces of bone
* Not embedded in the jaw (sit on jaw bone)
* Constantly being shed and replaced - Internal fertilization
* Males have pelvic claspers for
internal fertilization
-associated with pelvic fins - Lipid-filled liver
* Less dense than other body tissues and may be large to Facilitate buoyancy
* Skates & bottom dwelling species have smaller livers so they Sink to sea floor
Elasmobranchii- The Sharks
http://ipfactly.com/hammerhead-sharks/
Clade Selachii
• Highly diverse group
• Marine apex predators
• Many derived locomotor, sensory and behavioral adaptations
Elasmobranchii- The Sharks– Vision
Well developed vision permits vision at low
light
* Rod rich retina with platelike crystals of guanine : tapetum lucidum
-eye shine
-acts like mirror and reflects light
-adaptation that concentrates even low light
Elasmobranchii- The Sharks other sences
- Smell (chemoreception): - extremely acute
- Electroreception: to weak electric fields via the ampullae of Lorenzini
Elasmobranchii- The Sharks — Reproduction
- Internal fertilization
- Produce few offspring as a result
- Males have a clasper that deposits sperm into the female’s cloaca during copulation
- many speices are Oviparous some are viviparous
- Nourisment of embryo is either via a egg yolk (lecithotrophy and oviparous) or via the reproductive tract (matrotrophy and viviparous)
-lecithotrophy means “yolk of the egg” “acquisition of energy”
-matrotrophy means “mother” “acquisition of energy”
Oviparous sharks
have large eggs that have
projections that help it attach to
vegetation/substrates for protection
Vivipous sharks
Eggs are produced and retained inside the mother
* Young hatch in the female and stay until they are fully developed
- may eat other eggs or each other or fluids inside mother
-can be Non placental or placental
Elasmobranchii- Skates and Rays
• Clade Batoidea
• Dorsoventrally compressed with mouth and
gill slits on ventral surface (flat bois)
• Enlarged pectoral fin
• Fewer placoid scales
• Durophagous (flat teeth used to crush hard things)
• Some rays are venomous
• Skates are oviparous, rays viviparous
Holocephalli— Chimaerans
- Widely distributed in deep water (500+m)
- cartilaginous skeleton, oil filled liver
- Feed on invertebrates and small fish
- Extant chimaerans are oviparous
-take 10-12 yrs puberty because of slow metabolism
once/year with few resulting young
vulnerable to extinction
Evidence for oviparity being ancestral in chondrichyhes
Holocephalli Have unique features of Chondrichthyes:
• Four gill openings that are covered so it looks like one opening
• Teeth reduced to tooth plates
• Specialized sensory receptors on head
Osteichthyes- Bony Fishes/ Bony vertebrates: Charecteristics
- Ossified endoskeleton with endochondral bone, in addition to the dermal and perichondral bone.
- Enamel
-highly mineralized
-hardest mineral in body
-made of hydroxyapatite
-originates from epidermis - Gas containing structure (either gas bladder or lungs)
-some have both
-believed to be homologous
-lungs came first that turned into gas bladder
Osteichthyes are
Very diverse group consisting of > 66,000 species in 2 classes:
2 classes of osteichthyes
- Actinopterygii: ray-finned fishes
- Sarcopterygii: lobe-finned fishes
Bony Fish FIN Characteristics: Actinopterygians
The fins of Actinopterygian have lost the basals and the radials attach to the limb girdles
-can collapse fin against the body
-less turbulence
-more streamlined
Ancestral Osteichthyan fins
have a row of basals that interact with the limb girdle, followed radials and then fin rays that support the web of the fins
The fins of Sarcopterygians
have a single basal that articulates with the limb girdles
Actinopterygii 2 major divisions
- Non-teleosts
- Teleosts
Main differences between Non-telosts and teleosts include:
Jaw mobility: (greater in teleosts)
Tail shape : HOMOcercal (teleosts) vs
HETEROcercal (non-teleosts).
Non-teleosts include
- Polypteriformes (Bichirs and Reedfishes)
- Acipenseriformes (Sturgeons and Paddlefishes)
- Lepisosteiformes (Gars)
- Amiiformes (Bowfin)
Polypteriformes (Bichirs and Reedfishes)
- Live in stagnant freshwater
- Have 2 lungs which supplement gill
respiration and spiral intestine (increases surface area) with a pulmonary circulatory route
Acipenseriformes (Sturgeons and Paddlefishes)
- Have dermal head bones that are formed of cartilage (lost endochondral bone)
- Upper jaw is not fused to cranium
- Lung has been modified into non-respiratory gas bladder
Sturgeon
- Large, benthic fish with heterocercal tail
- Rows of armorlike scales: scutes (5 rows)
- Found in Northern Hemisphere
- Both freshwater & marine
– Marine forms go to freshwater to breed
Paddlefish
Two extant species of paddlefish
– Chinese paddlefish
* Yangtze River
* Bottom-feeding
* Not recorded since 2002
-long flat rostrum which is rich in ampules
– North American paddlefish:
* Mississippi River drainage
* Filter feeding
* Classified as vulnerable
Lepisosteiformes (Gars)
- Live in fresh water and estuarine water of North & Central America & Cuba
- Vascularized gas bladder (can be used as a lung)
- Move slowly but have a very fast strike to capture prey
-7 extant species
-interlocking multilayer scales that are very good armour
Amiiformes (Bowfin) (only 1 extant)
Generalist predator
live in weed filled lakes
thin layer of scales
have an eye spot on tail to confuse predators
Teleosts (4)
- Osteoglossomorpha (e.g., elephant nose fish)
- Elopomorpha (e.g., eel)
- Otocephala (e.g., herring, catfish)
- Euteleostei (e.g., salmon, etc. etc. etc.)
Osteoglossomorpha (e.g., elephant nose fish)
Bony Tongue
* Most primitive of the teleosts
* Some communicate and sense their
environment via electric discharges
Elopomorpha (Eels)
- Include bonefishes, tarpons and true eels
– Most live in marine environments but some are freshwater - Unique in that they have leptocephalus (small head) larvae
freshwater or marine environments
Profile: American eel (Anguilla rostrata)
- migrates from freshwater to sea to breed: catadromous
- Leptocephalus larvae float and drift to the coast where they morph into glass eels
-15-20 years until sexual maturity
Otocephala (herring, catfish, etc)
- Very diverse
– Includes marine schooling fish (important in food web) and
carnivorous freshwater fish - Many of the marine fish are anadromous
- Have two distinctive features
1. Weberian apparatus: Small bones that connect the swim bladder to the inner ear
2. Have a flight reaction due to release of pheromones from other fish
Euteleostei (salmon, etc. etc. etc)
• Includes thousands of species
• Diverse life history and morphology
how does swimming work?
Anterior to posterior sequential
contractions of muscle segments on one side of body and simultaneous relaxation on the other
modes of swimming
- Anguilliform: Typical of highly flexible fish
– Typical of true eels: Anguilliformes
- lots of movement in the body - Carangiform: undulations limited to the caudal region
* Typical of Jacks (Caranx spp.) - Ostraciiform: only caudal fin undulation
– Inflexible body
– Boxfishes, cowfishes, trunkfish - Labriform: Rapid undulation of the pectoral fins
– e.g. sticklebacks & wrasses - Rajiform: use elongated pectoral fins
-rays - Amiiform: use dorsal fin
-long dorsal fin
-undulates - Gymnotiform :use anal fin
-similar to amiiform but with anal tail - Balistiform: use dorsal and anal fins
Actinopterygian reproduction
- Most species lay eggs.
* Most are oviparous, but some are viviparous - Nutrition varies from lecithotrophy to
matrotrophy - Varying degrees of parental care
- Sex determination may be fixed for life, change sexes at some point,
hermaphroditic or completely female (no males)
-this varies on genetics and environment
-maximizes number of offspring produced
oviparity in actinopterygian
freshwater vs. marine reproduction:
Freshwater: small number of demersal (bury in gravel, place in nest, or attach to substrate) eggs
Marine:large number of eggs that are transparent and buoyant
terrestrial reproduction in actinopterygian
Many lay eggs at high tide, and eggs
develop over about 2 weeks, before the
next high tide
viviparity is seen in ___% of actinopterygians
- 3% but Seen in 12 lineages of teleosts
-seahorses, guppys, etc
adaptations for deep sea
Challenges of life in the deep sea include:
1. Absence of light
2. Little food
* Despite this there is diversity in the deep-sea fishes that live in the mesopelagic and bathypelagic zones
* Typically, species are:
* Small with sparse populations
* Resulting selection pressures include predator avoidance & finding a mate
-Many deep sea fish have large mouths and stomachs (need to be able to eat any prey you may encounter at those depths)
* Many contain photophores, which are
organs that produce light via a symbiosis with Photobacterium species
* May attract prey or be used to find
potential mates
Order Lophiliformes (Ceratoid Anlerfish)
-eggs float to top of water
-larvae develop and swim down
-female fully develops
-male only eats as a larvae
-once male is no longer a larvae, only purpose is to find a mate
-once mate is found the male will fuse to the female, connecting the circulatory systems
types of sarcopterygii
- Actinistians (Coelacanths) (1 extant)
- Dipnoans (Lungfishes) (3 extant)
- Tetrapodomorph fishes (the ancestors of tetrapods)
the coelacanths
Coelacanths arose in the Early Devonian
(~408 mybp)
– Thought to be extinct until ~70 years ago when one found in Indian Ocean
* Latimeria chalumnae ranges from 75cm-2m
* Another species was found in 1998 near Borneo (Latimeria menadoensis)
-Nocturnal
* Have a fat-filled “lung” that has ossified walls (vestigial organ)
* Viviparous fish
* Must have internal fertilization but copulation is not understood
The dipnoans (lungfishes)
-More related to tetrapods than coelacanths
* Australian lungfish have one lung, the others have 2 lungs.
* Lungs have subdivisions to increase surface area for gas exchange
types of lungfishes
-South American lungfish (Lepidosiren
paradoxa): little is known about it
-the males have a highly vascularized extensions under the pelvic fins to deliver oxygen to eggs
- Austrailian lungfish (Neoceratodus forsteri) has lobelike fins & heavy scales
- Inhabits permanent water bodies
- No parental care of offspring
- Does not depend on air to breathe
- African lungfish (Protopterus): four species
- Can “walk” underwater.
- Obligate air breathers
- Estivate in a U-shape in burrows during dry periods (covered in mucus with an opening for the mouth)
-water recedes sometimes and they burrow in the mud
differences of living on land
- Air is less viscous & less dense (less resistance)
* Need to overcome gravity - Gills collapse in air
- Heat capacity and conductivity
support and locomotion on land
- Fish are essentially ‘weightless’ in water
- Terrestrial tetrapods must have adaptations for
support and locomotion
– Skeleton must be rigid
– and as light as possible
-survival of the fittest
-must use energy effectively
-heavy bones are good for gravity but not for running
the skeletal system
- Made up of cartilage (more elastic than bone) and bone
- Bones are dynamic so that its internal structure can adjust to its changing demand
- In amniotes, bones are arranged in concentric layers around blood vessels
- The cylindrical units are called Haversian systems
- External layers of bone are dense/compact.
- Internal layers are spongy: cancellous bone
joints
- Joints are covered by articular cartilage which covers cancellous bone
- Entire joint is enclosed in a joint capsule which contains synovial fluid
axial and appendicular skeleton
Axial (skull, vertebral column, and sternum)
-cervical vertebra
-thoracic vertebra (connect to ribs)
-lumbar vertebra (do not connect to ribs but to ilium)
-sacral vertebra (pelvic girdle)
-caudal vertebra
Appendicular (pectoral and pelvic girdle, and limbs)
