A common organism to study in a biology lab is the hydra. The hydra belongs to a group of organisms known as cnidarians or sometimes called coelenterates. This phylum likewise includes pets such together the jellyfish and also sea anemone and the biology that make up coral reefs. The usual characteristic to all of these pets is the they have actually stinging cells located, known as cnidocytes, on their tentacles.

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Because castle belong come the animal kingdom, friend can also assume the all cnidarians room multicellular and heterotrophic - meaning they have to consume your food in part way. Countless cnidarians invest their resides attached to objects whereby they wait because that fish or other organisms to swim through them and become trapped by their tentacles.

Let"s to compare the main types of cnidarians. Sea anemones belong come the class Anthozoa, which converts to median "flower animal". Anemones room often really colorful and have thousands of tentacles that tide in the water currents when the main component of your body stays attached to a surface. They room pretty come look at, but deadly come fish the swim too close. The fish becomes paralyzed by the stinging cells and also eventually is pushed right into the anemone"s mouth, which is in ~ the center of the tentacles. The main body area includes a gastrovascular cavity, i beg your pardon is favor a stomach, wherein the fish is digested.

Coral is also related come the sea anemone, despite organisms in this group tend to be smaller and also live in colonies. Coral reefs space actually made from the skeletons of cnidarians the have develop up for countless years. A coral reef gives a residence to plenty of other s organisms, such as fish, octopus, crustaceans and even sharks. The good Barrier Reef off the shore of Australia is the biggest coral reef top top the planet.

The next group of cnidarians are the Scyphozoans, or jellyfish. These animals can move openly in the water. Basically, if you imagine a sea anemone upside down, climate you have actually a jellyfish. In fact, since cnidarians deserve to come in two forms, they have names for their body plans. The ones that sit top top a surface ar with their tentacles pointing up are referred to as polyps. The ones that swim v their tentacles pointing bottom are called medusas. Jellyfish acquire their food in the same way as other cnidarians, by capturing smaller animals with your tentacles. Unfortunately, occasionally swimmers have the right to accidentally come into contact with a jellyfish. In many cases, the sting from your tentacles is painful to humans, however not fatal.


The last group of cnidarians is the Hydrozoans, which consists of the hydra. This small organism is discovered in freshwater and also can quickly be grown and also studied in a biologic laboratory. The is large enough to it is in seen through the nude eye, yet if you want to see greater detail, location the hydra on a concave slide and also view the under a microscope. Friend will notice five or six tentacles surrounding the hydra"s mouth. Also under short power, you have the right to see the individual bump on the tentacles that note the place of the cnidocytes. Like anywhere cnidarians, the hydra has actually venom within this stingers used to capture and paralyze prey. In ~ the bottom of the hydra is its basal disk, i m sorry secretes a difficult substance because that attaching to surfaces. The hydra deserve to still relocate by floating and also by law a characteristics cartwheel where it flips end onto that tentacles and then pops ago to its original orientation.

You may even be able to see the hydra eat by placing a little organism, such together daphnia or brine shrimp on the slide. Once these biology swim close come the hydra, they will instantly be got by the tentacles and consumed. Because the hydra go not have actually a different opening because that waste, any material the cannot be digested is regurgitated out of the mouth.

Cnidarians perform not have actually a head or a mind or other organs that we find familiar to animals. The is exceptional that they deserve to live, eat, and also respond to their environment. Instead of a brain, their bodies have a nerve net, i m sorry is provided to coordinate your movements and also respond come the environment. Many cnidarians have the right to regenerate your tentacles or other damaged body parts. In fact, lock can also grow a whole brand-new body attached to their main body. This smaller version of us is referred to as a bud and is a type of asexual reproduction.

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Part A: - Citation. Because that each question below, do a notation within the write-up for whereby the answer is found. Usage the very same number a the question. One the exactly answer.

1. Come what kingdom carry out cnidarians belong? a. Animalia b. Porifera c. Cnidaria

2. What might a hydra eat? a. Birds b. Brine shrimp c. Jellyfish

3. I beg your pardon of the following remains greatly stationary, attached to surfaces? a. Jellyfish b. Sea anemone c. Hydra

4. A "bud" is created by a hydra together a way of: a. Defense b. Swimming c. Reproduction

5. Anthozoans were named such because: a. Lock looked like flowers b. Castle were found near Anthoa c. They have stingers

6. I m sorry cnidarians is most most likely to be learned in a biologic class? a. Jellyfish b. Sea anemone c. Hydra

7. I m sorry of the following qualities are common to every cnidarians? a. Stinging cells b. Live in oceans c. Medusa body form

8. Exactly how does a hydra eliminate wastes or undigested material?a. Exits through an anus b. Regurgitated indigenous the mouth c. Took in through the tentacles

9. Jellyfish belong to the Phylum ______ and the class ______.a. Cnidaria, Anthozoa b. Scyphozoa, Cnidaria c. Cnidaria, Scyphozoa

10. What structure permits a jellyfish (and various other cnidarians) to respond to its environment?a. Central nervous mechanism b. Nerve network c. Gastrovascular cavity

Part B: Summarizing

11. In a solitary sentence, determine the MAIN allude of the article.

12. Create a VENN diagram of 2 organisms mentioned in the post which compares and also contrasts the attributes of each.