Form to Function: Body Shape and Locomotion in the Aquatic Environment Fish History 550 million years ago >25 950 species today Natural selection has ensured that the mechanical systems [that] evolved in fishare
highly efficient with regard to the habitat and mode of life for each species. (Sfakiotakis et al. 1999, 237) Began as jawless anguilloform parasites Thompson 1971 Body Shape and Locomotion
Anguilloform Body and Caudal Fin (BCF) locomotion Whole body Elongated, slender, flexible bodies Subcarangiform/ Carangiform 2/31/3 of body Stiffer body and caudal fin Thunniform
Sfakiotakis et al. 1999 Stiff body Only caudal fin and attachment High crescent shaped caudal fin Ecology, Tradeoffs, and Conservation Found in every existing aquatic habitat
Many species endangered because of fishing pressures Habitat destruction Pollution Speed comes at the cost of maneuverability Have other types of locomotion for foraging and maneuvering Sea Turtles History
Family Cheloniidae 90 million years ago Evolved from amphibious form Order testudinomorpha is a sister taxon to crocodilia Ancestral forms were sequential quadrupedal paddlers Hindlimbs larger than
forelimbs Modern forms flysynchronous pectoral gait Forelimbs are much larger than hindlimbs Body Shape and Locomotion one of the fastest moving reptiles Hypertrophied forelimbs generate thrust on upstroke and
downstroke Lift based movement much like flying Hindlimbs are used as rudders/ elevators Davenport et al. 1984 Clawless, smooth, long, flat feet Short blunt head and neck Non-retractable
head and limbs Smooth flexible shell Tear drop shaped Rounded blunt front with gently tapered rear with flat bottomed hydrofoil shape Ecology, Tradeoffs, and Conservation
Habitat/Nesting site destruction/degradation Pet trade Caught in fishing nets Low reproductive rates Are unable to protect young Faster swimmers Efficient Pelagic Nearly invulnerable
to predation as adults Poor terrestrial Movement Nests Diet Jellyfish, eelgrass PENGUINS (Spheniscidae) History Tertiary period (60 million years ago) Evolved from flying birds similar to albatrosses
Earliest fossils from New Zealand Forelimbs shorter/broader than modern albatross, not as short/broad as modern penguins Semi-flexible elbows Places where muscle attached to bone suggests foot-propulsion Phylogeny disputed Body Shape and Locomotion Streamlined body Feathers Stiff reduces vibration and fluttering Tightly packed (up to 70 per square inch)
Oil gland near tail Bones Thick and dense Wing-propelled Flipper-shaped wings used in flying motion Allows thrust on upstroke and downstroke Ecology, Trade-offs, and Conservation 17 modern species Spend up to 75% of life in water Inhabit islands and remote parts of continents in Southern Hemisphere Cannot fly to escape predators Short legs make for inefficient walking on land (waddling) Tobagganing
All species protected under law, 3 considered at risk Threats include hunting, habitat destruction, global warming Non-native predators Cannot fly to escape dogs Oil pollution Have to surface to breathe CETACEANS (Whales, Dolphins, and Porpoises) History Eocene (40-50 million years ago) Terrestrial quadrupedal ancestor
from extinct suborder Archaeoceti Pakicetus Ambulocetus Rodhocetus Basilosauridae Durodontidae Quadrupedal paddling pelvic paddling dorsoventral undulation caudal oscillation Bejder and Hall 2002 Ambulocetus Thewissen and Bajpai 2001 Evolution: streamlined body, loss of fur,
backward shift of nostrils, transformation of forelimbs into flippers, flukes for swimming, loss of hindlimbs Body Shape and Locomotion Body shape for decreased drag Streamlined shape Loss of hindlimbs Thunniform swimming caudal oscillation Resembles a standing wave Lower third of body and caudal fluke moved through water in vertical plane Specialized caudal fluke lunate shape, provides thrust on both upstroke and downstroke
Vertebral column controls movement, dampens oscillations, acts as shock absorber Ecology, Trade-offs, and Conservation 76 extant species Inhabit every ocean of the world Size range from 4 feet and 100 pounds (dolphin) to 100 feet and 130 tons (blue whale) Disadvantage: they are large animals, one or two large young at a time that require parental care. This makes population growth slow. Many species are endangered Threats: commercial whaling, entanglement in fishing gear, collisions with ships, marine pollution Conclusion
s more efficient methods of swimming drag based paddling lift based oscillation Reducing drag Streamlining shape Eliminating extra limbs/claws/hair Variety of forms developing at different times from separate beginnings
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