hydra like animal
Hydras are interesting creatures. They do not have a brain, but they do have a nerve network distributed throughout their body. Despite this, they have a variety of behaviors.
Collecting Hydra
Hydras of various species are widespread in freshwater habitats. Some of them are so small that they are likely to be missed unless you look at them very carefully. Another thing that can make them difficult to see is the fact that they shrink into what looks like a small glob of jelly if disturbed. Hydra viridis can be small enough to live on the underside of the “leaves” of Lemna Minor, the lesser duckweed. Since this species is usually bright green due to the algae in its cells, it is extremely difficult to see in this situation.
Many people keep hydras in their aquariums, and the presence of the hydra is completely unknown to the aquarium owner, and the hydra causes no problems.
To collect Hydra, the easiest way is to go to a lake or similar body of fresh water and gently pass a fine net through the plants growing in the lake water. Hopefully you will have caught more than one type of Hydra in your web.
Animal
A hydra is a carnivorous animal. It feeds on small living beings. However, some hydras, notably Hydra viridis, have cells of zoochlorella algae on their bodies. These algae perform photosynthesis; producing sugars and other things that are used by both the algae and the Hydra. Hydra species with algae can live for a considerable time without taking prey. Presumably, the hydra also supplies the algae with their mineral needs. Some of these things, like nitrates, would actually be waste products of the Hydra’s metabolism.
This arrangement is similar to sea corals, which are related to the hydra.
food
Hydras catch small animals. In many cases, they eat microscopic creatures like ciliates, but a large hydra can eat adult Daphnia.
The tentacles on top of a hydra touch something in the water and stinging cells called nematocysts are activated, shooting small darts at the thing the hydra touched. These darts are attached to the hydra polyp by very fine threads. The darts are barbed and stick to potential prey, injecting venom. This is the same mechanism that jellyfish use in the sea. Many jellyfish have stings that are painful to humans and some can be fatal. As far as I know, humans can’t feel hydra stings.
The food is then rolled up and transferred to the hydra’s “mouth” at the top, surrounded by the tentacles. The food is then digested as much as the hydra is capable of and the nutrients are adsorbed. The undigested parts of the hydra’s food are expelled through the “mouth”.
Breathing
Hydras do not have specialized organs to absorb dissolved oxygen from the water. This is done through the skin. Apparently the movement of oxygen into the hydra and carbon dioxide out is by diffusion, although active transport of the gases cannot be easily ruled out.
Hydras that have algae would also obtain oxygen as a waste product of photosynthesis carried out by the algae. In turn, the algae would use carbon dioxide, which is a waste product of Hydra metabolism.
movement
Hydras are sessile. That is, they are attached to surfaces instead of floating freely like jellyfish. But they have ways of moving. They can move slowly around the base flowing like an amoeba. They can also move like a caterpillar by coiling their tops together, alternating between tops and bottoms. The third way they can move is to break free from their surface and float away in hopes of finding a better place to live.
Light
Hydras do not have eyes or similar specialized light-sensitive organs. However, their bodies allow light to pass through them. The nerves seem to have some sensitivity to light, so it’s not surprising that hydras can sense both light and dark.
Most Hydra species avoid light, but those with algae are attracted to light. This is to be expected because hydras with algae need light for photosynthesis, while species without algae are more visible to both their prey and predators in well-lit areas. This suggests that there is a great advantage to the Hydra in being able to form a symbiotic association with algae.
Immortality Hydra
Of course living things can die. More than that, the animals and plants that we are most familiar with will age and die from things related to aging, this is known as senescence. This does not apply to all living things. A bacterium can divide into 2 almost identical “daughter” cells. That is, both new cells have the same right to be considered as original. Apparently this has been going on for as long as bacteria have been around.
Aside from things like bacteria, there are some animals that may not age in the same sense as most. It can be difficult to prove this, although it is often possible to disprove it.
Some studies suggest that the hydra does not die of old age and, in theory, could live forever. The life of an individual hydra is dangerous and the average lifespan is quite short. Although it may be difficult to prove, a very old Hydra could exist.
Brain
A brain is a concentration of nerves. In theory, nothing prevents an animal from having more than one brain. In fact, it appears that some types of dinosaurs had two brains.
Hydras have no brain in this sense. Instead, they have a nerve network fairly evenly distributed throughout the body. This works for your lifestyle.
Reproduction
The most common way for Hydras to reproduce is asexually, with a new, genetically identical individual springing from the parent Hydra. Hydras can multiply very rapidly under favorable conditions.
They can also reproduce sexually. Some types form hardy eggs, so drying out a pond will not necessarily eliminate all hydras.
Regeneration
If a hydra is cut, as long as each piece has all three types of hydra vegetative cells, it can become a complete animal.