Presentation on theme: "Adaptations of Organisms to Lotic Habitats By: Victoria Lewis Natalie Jackson Nancy Jones Ruth Starr-Keddle."— Presentation transcript:
Adaptations of Organisms to Lotic Habitats By: Victoria Lewis Natalie Jackson Nancy Jones Ruth Starr-Keddle
Introduction H In lotic systems, the velocity of flowing water is a major influence on: Àsubstrate type, with boulders deposited in fast-flow and fine sediments in slow-flow areas, Átransport of particles, either as a food source for filter- feeders or, during peak flows, as scouring agents, Âmaintenance of high levels of dissolved oxygen.
H A stream or river contains heterogeneous micro-habitats interspersed with; Àriffles, Ádeeper natural pools, Âerosion of banks, Ãsediments deposited, Äareas of unstable, shifting sandy substrates.
Adaptations Of Aquatic Plants To Lotic Habitats H Leaves & stems within, or floating on Water. H Upper leaves or shoots able to grow above the water, lower ones able to grow submerged. ÀTall monocotyledons- Grasses, sedges & rushes ÁShort dicotyledons-the fringing herbs-typically found fringing the sides of small brooks ÂShort monocotyledons, mainly grasses, again frequently at the sides of brooks ÃA very few tall dicotyledons H Bank plants growing above normal water level, flooded after heavy rain.
Adaptations of Insects to Lotic Habitats H Morphological Adaptations ÀDorsoventral Flattening ÁCase Construction ÂSuckers ÃSilk Nets ÄSize H Behavioural Adaptations ÀUse of Drift ÁBurrowing
Morphological Adaptations H Dorsoventral Flattening ÀAllows the organism to stay close to the substrate where there is a layer of still water. An example of this is the Water Penny. H Case Construction ÀA variety of case shapes made by caddis fly larvae assist in streamlining and act as a ballast.
Morphological Adaptations H Suckers ÀAllows the insect to stick to quite smooth exposed surfaces such as rock faces or in waterfalls, some Diptera larvae use this. H Silk Nets ÀUsed to maintain position in flow. Blackfly larvae attach their claws to a silk pad attached to a rock.
Morphological Adaptations H Size ÀBeneficial to be smaller and have flexible bodies, allowing them to live in the bed (benthos) of the stream between the boulders, stones and pebbles.
Behavioural Adaptations H Drift ÀA drifting stategy can be used to move from an unsuitable location. Some insects such as Baetis follow a diurnal periodic pattern of drift. Catastrophic Drift is used by some as a response to physical disturbance.
Behavioural Adaptations H Burrowing ÀInsects will burrow deep into the substrate (the hyporheic zone) where they can avoid fluctuations in the environment.
Adaptations of Vertebrates to Lotic Habitats H All 5 phyla possess species adapted to life in lotic habitats;fish, amphibians, reptiles, birds, and mammals. H Streamlined body shapes to reduce friction in water. H Some more specialised adaptations in life history, physiology and morphology.
Adaptations of Fish H 8,500 freshwater species. H Salmonoids & Lampreys; DIAROMOUS ÀLampreys larval stage; AMOCOETE ÁSalmonoids can vary their growth rates H CATADROMOUS, e.g. eels H DIADROMOUS GLOBOID; larval stage at sea.
Adaptations of Amphibians H 2 common families; URODELA (salamanders & newts), ANURA (frogs & toads). H Eggs laid in freshwater. H Larval stage possess gills, but also use skin for gaseous exchange. H Adults possess lungs but still use their skin as well for gaseous exchange.
Adaptations of Reptiles H Some species of snake and turtle are found in lotic habitats. H Crocodiles; ÀEyes, nostrils & ears on top of head. ÁNICTITATING membrane to cover eyes. ÂValves to close ears & nostrils. ÃLong thin body with short legs good for sinuous swimming movements.
Adaptations of Birds H Dippers; ÀDense, waterproof feathers. ÁNasal flaps. ÂWings used like flippers when in water. ÃNICTITATING membrane. H Ducks; ÀFew species are confined to a lotic habitat. ÁHarlequin duck, truly lotic.
Adaptations of Mammals H Few aquatic species exclusively reside in lotic habitats. H Otters; lutra (genus) ÀStreamlined body shape. ÁBroad flat tail involved in sinuous swimming movements. ÂShort dense fur impermeable to water. ÃLarge lung capacity allowing long dives. ÄPartially webbed feet for swimming.
H Platypus; ÀWebbed feet, short fur, Lacks external ears. ÀFeeds on bethic invertebrates. ÀBill covered with soft skin possessing many electrosensors. ÀBroad flat tail used as rudder when diving & surfacing H River Dolphin; Àonly mammal confined to lotic habitats. ÁPoor vision. ÂNarrow, very sensitive sonic beam for location of food & obstacles. ÃSmaller body size than marine dolphin.
Conclusion H Some plants and invertebrates have specific adaptations to the lotic environment, and vertebrates tend to be suited to an aquatic environment. H All are linked together in the lotic environment, ie. Submerged plants provide egg-laying sites for invertebrates and fish, and lurking sites for predators.