Crayfish are invertebrates which means they don't have a backbone. They are also arthropods, which means that they have a protective exoskeleton on the outside of their body. Other arthropods include insects, spiders, and centipedes. Crayfish continually shed their exoskeleton and regrow a new one. During this transition is when they are most vulnerable to predators because they aren't protected by their outer shell.
Crayfish are found all over the world in many different freshwater environments, such as rivers, creeks, springs, and swamps. But this doesn't necessarily mean that you will be able to find them. They are somewhat cryptic because they dig out homes for themselves under rocks and blend in well with their environment. Crayfish will ardently defend this dwelling against intruders using their strong front claws
<span>third layer of the canopy
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Early pre-cambrian period the atmosphere consisted only of nitrogen and carbon dioxide without oxygen.
<span>A Prokaryotic cell does not contain a nucleus. It only contains one chromosome and is a single-celled organism. It was the only form of life on earth for millions of years. Examples of a Prokaryotic cell are the different types of bacteria present today.
</span><span>Autotrophs obtain energy by the process of photosynthesis. Any living organism need energy to survive and autotrophs are no different. Two types of autotrophs are present and they are Photoautotrophs and Chemoautotrophs. The Photoautotrophs rely on the energy produced during the process of photosynthesis and the Chemoautotrophs get their energy from most of the inorganic substances. Phtoautotrophs actually get their energy from the sunlight and then convert it into reusable form. In case of Chemoautotrophs ammonia is an important source of energy for them.</span>
They are called transmission electron microscopes.
