Marine Vertebrates:Fishes (part 2)

Fishes

Phylum Chordata Subphylum Vertebrata 3 Classes:

Class Agnatha (jawless fishes) Class Chondrichthyes (cartilaginous fishes) Class Osteichthyes (bony fishes)

Fishes - Anatomy Cartilaginous fishes:

Ventral mouth Heterocercal tail (caudal fin) Placoid scales

“dermaldenticles”

Bony fishes: Terminal mouth Homocercal tail Cycloid or ctenoid scales

cycloid

ctenoid

Fishes - Anatomy

Cartilaginous fish skeleton:

Fishes - Anatomy

http://www.marinebiodiversity.ca/shark/english/images/porbeagle%20skeleton%20for%20web.jpg

Bony fish skeleton:

Fishes - Anatomy

http://www.infovisual.info/02/img_en/034%20skeleton%20of%20a%20fish.jpg

Fishes - Buoyancy

Bony fish – swim bladder (gas) Cartilaginous fish –

Swim, get lift from stiff fins Large, oil-filled liver Cartilage half as dense as bone

Fishes - Locomotion

http://www.buschgardens.org/infobooks/BonyFish/images/muscle.gif

Muscle up to 75% of body weight Muscle bands – myomeres (flake when cooked) Red muscle – sustained swimming White muscle – burst swimming

http://www.earthlife.net/fish/muscles.html

Fishes - Locomotion

http://www.buschgardens.org/infobooks/BonyFish/images/caudalfi.GIF

Homocercal caudal fins by shape:

Slowest →

Fast → ← Fastest

← Slow

http://www.dfw.state.or.us/mrp/salmon/FishID/Heterocercal.jpg

Heterocercal caudal fins:

http://static.howstuffworks.com/gif/willow/flying-fish-info0.gif

Fishes - Locomotion

Swimming modes:

Fishes - Locomotion

Built for speed – Pacific sailfish has high speed bursts 70+ mph

Fishes - Respiration

Cartilaginousfish

Bony fish(more efficient)

5-7 pairs of gills Gill slit openings

4 pairs of gills Operculum gill cover

Fishes - Respiration

http://elasmodiver.com/images/Cortez-round-stingray-04.jpg http://blogs.southflorida.com/citylink_dansweeney/Southern_sting_ray.jpg

Spiracles important for rays when buried

Fishes - Respiration

Gills maximize oxygen diffusion: High surface area Counter-current flow (oxygen concentration of water always higher than blood)

Fishes - Respiration

“Warm-blooded” fish: Epipelagic sharks, tunas, billfishes Counter-current flow retains muscle heat Body surface stays water temperature Body core has elevated temperature

Fishes - Feeding

Large mouth, tear chunks or swallow fish whole Small mouth,

small prey

Small mouth, small prey

Hard beak, graze algae and coral

Large mouth, filter feeder (plankton)

Largest species: Whale sharks (up to 60 ft) Basking sharks (up to 50 ft) Filter feeders (eat plankton)

Whale (Rhincodon typus) Basking (Cetorhinus maximus)

Fishes - Feeding

Fishes - Digestion

Fishes - Osmoregulation

Equal solutes by adding urea

Lower solutes, water loss

Fishes – Sensory Organs Vision Taste buds Smell – olfactory sacs, nostrils Sound – inner ear, otoliths (bones)

http://www.ncdc.noaa.gov/paleo/pubs/andrus2002/otolith-md.gif

http://www.marinebiodiversity.ca/otolith/english/images/cod6oto.jpg

Fishes – Sensory Organs

Vibrations – lateral line (for hearing, too)

Fishes – Sensory Organs

Electroreception – ampullae of Lorenzini (cartilaginous fishes only)

small holes

http://www.seaworld.org/infobooks/Sharks&Rays/images/ampullae.gif

Fishes – Schooling

Use senses to coordinate (vision, sound, lateral line) Protection from predation

Safety in numbers Visual confusion

Feeding Mating Swimming efficiency

http://image14.webshots.com/14/5/22/94/170152294GjijRv_fs.jpg

http://image03.webshots.com/3/4/24/9/6942409XjGFEFguyY_ph.jpg

Fishes – Reproduction

Fertilization External – bony fishes Internal – cartilaginous

http://www.pbs.org/wnet/nature/files/2008/10/286_lifeed_behind1.jpg

http://www.gloversreef.org/grc/spawning.jpg http://www.flmnh.ufl.edu/fish/education/questions/claspers.jpg

http://www.charkbait.com/article/Scan5sm.jpg

Fishes – Reproduction

Development Oviparous (most bony fishes, some cartilaginous):

External eggs, yolk

http://www.ufz.de/data/bioindicator-fish-eggs2455.jpg

Fishes – Reproduction

Development Ovoviviparous:

Internal eggs, yolk, live-birth

Viviparous: Internal eggs, nutrition from mother, live-birth

http://www.west.asu.edu/achristie/hsw4kids/animals/sharks/birtha.jpg

Fishes – Reproduction

Asexual – parthenogenesis (“virgin births”)

Very rare Female sharks in captivity Female offspring (genetic clones)

http://www.sciencedaily.com/images/2008/10/081010173054-large.jpghttp://marinebio.org/upload/_05/Sphyrna_tiburo1.jpg

Bonnethead – 2001 Black-tip – 2008

Fishes – Reproduction

Strategies Many small eggs (tarpon – 100 million eggs each spawn) Fewer large eggs (more work)

http://www.soc.soton.ac.uk/GDD/hydro/atmu/ecology/chapter5/sgtmjr.jpg

Planktonic fish larvae

http://www.coralreeffish.com/larvae.htm

Fishes – Development

Coastal fish use estuaries as nurseries

Fishes – Development

Cartilaginous vs. Bony FishesCartilaginous Bony

Scales placoid cycloid, ctenoid

Mouth ventral terminal

Tail lobes unequal (heterocercal) equal (homocercal)

Gills 5-7 pairs, slits 4 pairs, covers

Position in water fins, lower density (cartilage and oily liver)

swim bladder

Osmoregulation urea (equal solutes), rectal gland

less solutes, gill excretion

Sensory ampullae of Lorenzini, lateral line

lateral line

Reproduction(fertilization, development, strategy)

internal, variety, fewer offspring

external, mostly oviparymore offspring