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Adaptations of Organisms to Lotic Habitats

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Presentation on theme: "Adaptations of Organisms to Lotic Habitats"— Presentation transcript:

1 Adaptations of Organisms to Lotic Habitats
By: Victoria Lewis Natalie Jackson Nancy Jones Ruth Starr-Keddle

2 Introduction In lotic systems, the velocity of flowing water is a major influence on: substrate type, with boulders deposited in fast-flow and fine sediments in slow-flow areas, transport of particles, either as a food source for filter-feeders or, during peak flows, as scouring agents, maintenance of high levels of dissolved oxygen.

3 A stream or river contains heterogeneous micro-habitats interspersed with;
riffles, deeper natural pools, erosion of banks, sediments deposited, areas of unstable, shifting sandy substrates.

4 Adaptations Of Aquatic Plants To Lotic Habitats
Leaves & stems within, or floating on Water. Upper leaves or shoots able to grow above the water, lower ones able to grow submerged. Tall monocotyledons- Grasses, sedges & rushes Short dicotyledons-the fringing herbs-typically found fringing the sides of small brooks Short monocotyledons, mainly grasses, again frequently at the sides of brooks A very few tall dicotyledons Bank plants growing above normal water level, flooded after heavy rain.

5 Adaptations of Insects to Lotic Habitats
Morphological Adaptations Dorsoventral Flattening Case Construction Suckers Silk Nets Size Behavioural Adaptations Use of Drift Burrowing

6 Morphological Adaptations
Dorsoventral Flattening Allows the organism to stay close to the substrate where there is a layer of still water. An example of this is the Water Penny. Case Construction A variety of case shapes made by caddis fly larvae assist in streamlining and act as a ballast.

7 Morphological Adaptations
Suckers Allows the insect to stick to quite smooth exposed surfaces such as rock faces or in waterfalls, some Diptera larvae use this. Silk Nets Used to maintain position in flow. Blackfly larvae attach their claws to a silk pad attached to a rock.

8 Morphological Adaptations
Size Beneficial to be smaller and have flexible bodies, allowing them to live in the bed (benthos) of the stream between the boulders, stones and pebbles.

9 Behavioural Adaptations
Drift A 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.

10 Behavioural Adaptations
Burrowing Insects will burrow deep into the substrate (the hyporheic zone) where they can avoid fluctuations in the environment.

11 Adaptations of Vertebrates to Lotic Habitats
All 5 phyla possess species adapted to life in lotic habitats;fish, amphibians, reptiles, birds, and mammals. Streamlined body shapes to reduce friction in water. Some more specialised adaptations in life history, physiology and morphology.

12 Adaptations of Fish 8,500 freshwater species.
Salmonoids & Lampreys; DIAROMOUS Lampreys larval stage; AMOCOETE Salmonoids can vary their growth rates CATADROMOUS, e.g. eels DIADROMOUS GLOBOID; larval stage at sea.

13 Adaptations of Amphibians
2 common families; URODELA (salamanders & newts), ANURA (frogs & toads). Eggs laid in freshwater. Larval stage possess gills, but also use skin for gaseous exchange. Adults possess lungs but still use their skin as well for gaseous exchange.

14 Adaptations of Reptiles
Some species of snake and turtle are found in lotic habitats. Crocodiles; Eyes, nostrils & ears on top of head. NICTITATING membrane to cover eyes. Valves to close ears & nostrils. Long thin body with short legs good for sinuous swimming movements.

15 Adaptations of Birds Dippers; Ducks; Dense, waterproof feathers.
Nasal flaps. Wings used like flippers when in water. NICTITATING membrane. Ducks; Few species are confined to a lotic habitat. Harlequin duck, truly lotic.

16 Adaptations of Mammals
Few aquatic species exclusively reside in lotic habitats. Otters; lutra (genus) Streamlined body shape. Broad flat tail involved in sinuous swimming movements. Short dense fur impermeable to water. Large lung capacity allowing long dives. Partially webbed feet for swimming.

17 Platypus; River Dolphin; Webbed feet, short fur, Lacks external ears.
Feeds on bethic invertebrates. Bill covered with soft skin possessing many electrosensors. Broad flat tail used as rudder when diving & surfacing River Dolphin; only mammal confined to lotic habitats. Poor vision. Narrow, very sensitive sonic beam for location of food & obstacles. Smaller body size than marine dolphin.

18 Conclusion Some plants and invertebrates have specific adaptations to the lotic environment, and vertebrates tend to be suited to an aquatic environment. All are linked together in the lotic environment, ie. Submerged plants provide egg-laying sites for invertebrates and fish, and lurking sites for predators.

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