Cray Fish Lab Report

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1. Introduction:
This report will mainly focus on some adaptation features creatures which live in the lake and wetland freshwater habitat have.

2. The adaptive features of animals:
i. Adaptation to live in the habitat lack of oxygen
A. Crayfish:
Crayfish lives in fresh water stream, which is an aquatic environment. The oxygen level in fresh water upper stream is higher than the lower stream, but the oxygen concentration is still low. The gills of crayfish are much bigger than the size at first glance. They occupied under the cephalothorax carapace in branched-shape and provided a large surface area to volume ratio to carry out gas exchange. Fresh water will be pulled into the cavity by the movement of the “gill bailers”. Also, many crayfish
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The reason why some animals can still attach on slippery stone firmly is due to the muscular portion of foot and secretion of mucus. With this adaptive features, fresh water snails can live or move across the stone in water stream with fast water flow. Hence, they won't be flushed away.

B. Ephydridae( skater / water strider)
Ephydridae, also called water skater or water strider are well adapted to live in the lower stream, where the speed of water flow is nearly 0m/s. It can move quickly and continuously on the water surface. For the reason why it can float and move quickly on the water surface, it is due to their velvety hair on their legs except for the front legs which are highly hydrophilic and the water tension is strong enough to support the weight of skater.
Even storm occurs in water stream, skater can also stand rightly on the water surface. This is because the hair on the legs are very small in diameter, which are about 1/30 of human hair. Thus, air can be trapped within the densely packed hair and isolate water from its body. Rather than water tension, the velvety hair is the main reason that allows water striders to float on the water surface.
With this adaptation, skater can escape from predator and prey on insects more easily because they can act before target starting to
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The adaptive features of plants:
i. Leaves:
Various kinds of the plants’ leaves have adapted to the freshwater habitat depending on where they locate. This report will mainly focus on two adaptive features of leaves: i.e. underwater leaves and floating leaves.

A. Underwater leaves:
This kinds of leaves often exist on the plants whose whole body grow underwater in the water stream. As some region in water stream is deep, which is about 4-5metres, so the light diffused to the bottom is few. In order to absorb sufficient defused light, this kind of leave is very thin and just appear as strands of algae so as to increasing the surface area for absorbing maximum amount of sun light.

B. Floating leaves:
This kind of features are often common. The leaves are broad and have lacunae which contains gas which can provide the leaves buoyancy so that they can flow on the water to obtain sunlight directly. In this case it can use abundant light to conduct photosynthesis and gain more nutrition.

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