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
Answer: (SL) Semilunar Valves
Explanation:
A high biodiversity tally may indicate that some of its organisms may be able to survive drastic environmental changes. If there weren't at least a few organisms that contribute to biodiversity, most of the biotic Earth would be gone by now.
For example, woolly mammoths were unable to adapt to the up-and-coming warmth of the poles. Because they lacked biodiversity among their species, all of them died out and weren't able to adapt to the heat.
I hope I helped!
D. that is the correct answer
It may be perfectly healthy that their newborn is sleeping this long so unless they start displaying other strange symptoms that cause concern, there is no need to worry. They could suggest that they are concerned to the midwife if they feel anxious, to get a professional opinion.
