They can live at the deepest depths. Tasks and exercises for the school course of general ecology
Contains chloroplasts. Algae have different shapes and sizes. They live mainly in water to the depths where light penetrates.
Among the algae, there are both microscopically small and giant ones, reaching a length of over 100 m (for example, the length of the brown alga macrocystis pear-shaped is 60-200 m).
Algae cells contain special organelles - chloroplasts, which carry out photosynthesis. At different types they have different shapes and sizes. Algae absorb mineral salts and carbon dioxide necessary for photosynthesis from the water with the entire surface of the body and release oxygen into the environment.
Multicellular algae are widespread in freshwater and marine reservoirs. The body of multicellular algae is called the thallus. A distinctive feature of the thallus is the similarity in the structure of cells and the absence of organs. All cells of the thallus are arranged in almost the same way, and all parts of the body perform the same functions.
Algae reproduce asexually and sexually.
asexual reproduction
Single-celled algae reproduce, as a rule, by division. Asexual reproduction of algae is also carried out through special cells - spores, covered with a shell. Spores of many species have flagella and are able to move independently.
sexual reproduction
Algae are also characterized by sexual reproduction. In the process of sexual reproduction, two individuals participate, each of which passes on its chromosomes to the offspring. In some species, this transfer is carried out by merging the contents of ordinary cells, while in others, special sex cells, called gametes, stick together.
Algae live mainly in water, inhabiting numerous marine and freshwater reservoirs, both large and small, temporary, both deep and shallow.
Algae inhabit water bodies only at those depths to which sunlight penetrates. Few species of algae live on rocks, tree bark, and soil. For living in water, algae have a number of adaptations.
Adaptation to the environment
For organisms that live in the oceans, seas, rivers and other bodies of water, water is the habitat. The conditions of this environment are noticeably different from the conditions on the ground. Reservoirs are characterized by a gradual decrease in illumination as they dive deeper, fluctuations in temperature and salinity, low oxygen content in water - 30-35 times less than in air. In addition, the movement of water poses a great danger to seaweed, especially in the coastal (tidal) zone. Here, algae are exposed to such powerful factors as surf and wave impacts, ebb and flow (Fig. 39).
The survival of algae in such harsh conditions of the aquatic environment is possible thanks to special adaptations.
- With a lack of moisture, the shells of algae cells thicken significantly and become saturated with inorganic and organic substances. This protects the body of algae from drying out during low tide.
- The body of seaweed is firmly attached to the ground, therefore, during the surf and wave impacts, they relatively rarely break away from the ground.
- Deep-sea algae have larger chloroplasts with a high content of chlorophyll and other photosynthetic pigments.
- Some algae have special bubbles filled with air. They, like floats, keep the algae at the surface of the water, where it is possible to capture the maximum amount of light for photosynthesis.
- The release of spores and gametes in algae coincides with the tide. The development of the zygote occurs immediately after its formation, which does not allow the ebb to carry it into the ocean.
Algae representatives
brown algae
Kelp
The seas are inhabited by algae, which have a yellow-brown color. These are brown algae. Their color is due to the high content of special pigments in the cells.
The body of brown algae looks like threads or plates. A typical representative of brown algae is kelp (Fig. 38). It has a lamellar body up to 10-15 m long, which is attached to the substrate with the help of rhizoids. Laminaria reproduces asexually and sexually.
Fucus
Fucus forms dense thickets in shallow water. Its body is more dissected than that of kelp. In the upper part of the thallus there are special air bubbles, thanks to which the body of the fucus is held on the surface of the water.
On this page, material on the topics:
red algae are capable of photosynthesis
algae number of species
algae have
why algae inhabit the rivers of the lake only where sunlight penetrates
algae and their adaptation to the environment
Questions for this article:
What organisms are algae?
It is known that algae inhabit the seas, rivers and lakes only at those depths to which sunlight penetrates. How can this be explained?
What is common and distinctive in the structure of unicellular and multicellular algae?
What is the main difference between brown algae and other algae?
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Within the biosphere, one can distinguish four main habitats. These are the aquatic environment, the ground-air environment, the soil and the environment formed by the living organisms themselves.
Water environment
Water serves as a habitat for many organisms. From water, they receive all the substances necessary for life: food, water, gases. Therefore, no matter how diverse aquatic organisms are, they must all be adapted to the main features of life in aquatic environment. These features are determined by the physical and chemical properties water.
Hydrobionts (inhabitants of the aquatic environment) live in both fresh and salt water and are divided into \ (3 \) groups according to their habitat:
- plankton - organisms that live on the surface of water bodies and move passively due to the movement of water;
- nekton - actively moving in the water column;
- benthos - organisms that live at the bottom of water bodies or burrow into silt.
In the water column, many small plants and animals constantly hover, leading life in suspension. The ability to soar is provided not only by the physical properties of water, which has a buoyant force, but also by special adaptations of the organisms themselves, for example, numerous outgrowths and appendages that significantly increase the surface of their body and, therefore, increase friction against the surrounding liquid.
The body density of animals such as jellyfish is very close to that of water.
They also have a characteristic body shape resembling a parachute, which helps them to stay in the water column.
Active swimmers (fish, dolphins, seals, etc.) have a spindle-shaped body, and limbs in the form of flippers.
Their movement in the aquatic environment is facilitated, in addition, due to the special structure of the outer covers, which release a special lubricant - mucus, which reduces friction against water.
Water has a very high heat capacity, i.e. ability to store and retain heat. For this reason, there are no sharp temperature fluctuations in water, which often occur on land. Very deep waters can be very cold, but due to the constant temperature, animals have been able to develop a number of adaptations that ensure life even in these conditions.
Animals can live in the vast ocean depths. Plants, on the other hand, survive only in the upper layer of water, where the radiant energy necessary for photosynthesis enters. This layer is called photic zone .
Since the surface of the water reflects most of the light, even in the most transparent ocean waters, the thickness of the photic zone does not exceed \(100\) m. Animals of great depths feed either on living organisms or on the remains of animals and plants that constantly sink down from the upper layer.
Like terrestrial organisms, aquatic animals and plants breathe and require oxygen. The amount of oxygen dissolved in water decreases with increasing temperature. Moreover, oxygen dissolves worse in sea water than in fresh water. For this reason, water high seas tropical zone are poor in living organisms. Conversely, the polar waters are rich in plankton - small crustaceans that feed on fish and large cetaceans.
Salt composition of water is very important for life. Ions \(Ca2+\) are of particular importance for organisms. Mollusks and crustaceans need calcium to build their shells or shells. The concentration of salts in water can vary greatly. Water is considered fresh if one liter contains less than \ (0.5 \) g of dissolved salts. Sea water is characterized by constant salinity and contains an average of \ (35 \) g of salts per liter.
Ground air environment
The terrestrial air environment, mastered in the course of evolution later than the water one, is more complex and diverse, and it is inhabited by more highly organized living organisms.
The most important factor in the life of the organisms living here are the properties and composition of the surroundings. air masses. The density of air is much lower than the density of water, therefore, terrestrial organisms have highly developed supporting tissues - the internal and external skeleton. The forms of movement are very diverse: running, jumping, crawling, flying, etc. Birds and some types of insects fly in the air. Air currents carry plant seeds, spores, microorganisms.
Air masses are constantly in motion. Air temperature can change very quickly and over large areas, so land-dwelling organisms have numerous adaptations to withstand or avoid sudden changes in temperature.
The most remarkable of them is the development of warm-bloodedness, which arose precisely in the ground-air environment.
important for plant and animal life chemical composition air (\(78%\) nitrogen, \(21%\) oxygen and \(0.03%\) carbon dioxide). Carbon dioxide, for example, is the most important raw material for photosynthesis. Air nitrogen is necessary for the synthesis of proteins and nucleic acids.The amount of water vapor in the air (relative humidity) determines the intensity of transpiration processes in plants and evaporation from the skin of some animals. Organisms living in conditions of low humidity have numerous adaptations to prevent severe water loss. For example, desert plants have a powerful root system capable of sucking water into the plant from a great depth. Cacti store water in their tissues and use it sparingly. In many plants, to reduce evaporation, the leaf blades are turned into spines. Many desert animals go into hibernation during the hottest period, which can last several months.
The soil - this is the upper layer of land, transformed as a result of the vital activity of living beings. This is an important and very complex component of the biosphere, closely related to its other parts. Soil life is extraordinarily rich. Some organisms spend their whole life in the soil, others - part of their life. Between soil particles there are numerous cavities that can be filled with water or air. Therefore, the soil is inhabited by both aquatic and air-breathing organisms. Soil plays an important role in plant life.
Living conditions in the soil are largely determined by climatic factors, the most important of which is temperature. However, as they sink into the soil, temperature fluctuations become less and less noticeable: daily temperature changes quickly fade, and as the depth increases, seasonal temperature changes.
Even at a shallow depth in the soil, complete darkness reigns. In addition, as it sinks into the soil, the oxygen content decreases and the carbon dioxide content increases. Therefore, only anaerobic bacteria can live at a considerable depth, while in the upper layers of the soil, in addition to bacteria, fungi, protozoa, roundworms, arthropods, and even relatively large animals that make passages and build shelters, for example, moles, shrews, and mole rats, are found in abundance.
The environment formed by living organisms themselves
Obviously, the conditions of life inside another organism are characterized by greater constancy in comparison with the conditions of the external environment.
Therefore, organisms that find a place for themselves in the body of plants or animals often completely lose the organs and systems necessary for free-living species. They do not have developed sense organs or organs of movement, but there are adaptations (often very sophisticated) for keeping in the host's body and effective reproduction.
Sources:
Kamensky A.A., Kriksunov E.A., Pasechnik V.V. Biology. Grade 9 // DROFA
Kamensky A.A., Kriksunov E.A., Pasechnik V.V. Biology. General biology (a basic level of) 10-11 class // DROFADeep water is the lower level of the ocean, located at a distance of more than 1800 meters from the surface. Due to the fact that only a small fraction of light reaches this level, and sometimes light does not reach at all, historically it was believed that there was no life in this layer. But in fact, it turned out that this level is simply teeming with different forms of life. It turned out that with each new dive to this depth, scientists miraculously find interesting, strange and outlandish creatures. Below are ten of the most unusual of them:
10. Polychaete Worm
This worm was caught this year at the bottom of the ocean at a depth of 1200 meters off the northern coast of New Zealand. Yes, it can be pink, and yes, it can reflect light in the form of a rainbow - but despite this, the polychaete worm can be a ferocious predator. The "tentacles" on its head are sensory organs designed to detect prey. This worm can twist its throat in order to grab a smaller creature - like an Alien. Fortunately, this type of worm rarely grows more than 10 cm. They also rarely come across our path, but are often found near hydrothermal vents on the ocean floor.9 Squat Lobster
These unique lobsters, which look rather intimidating and look like headcrabs from the Half-Life game, were discovered on the same dive as the polychaete worm, but at a greater depth, about 1400 meters from the surface. Despite the fact that squat lobsters were already known to science, they had never seen this species before. Squat lobsters live at depths of up to 5,000 meters, and are distinguished by their large front claws and compressed bodies. They can be detritivores, carnivores, or herbivores that feed on algae. Not much is known about individuals of this species, in addition, representatives of this species were found only near deep-sea corals.8. Carnivorous Coral or Carnivorous Coral
Most corals get nutrients from photosynthetic algae that live in their tissues. This also means that they must live within 60 meters of the surface. But not this species, also known as Sponge-Harp. It was discovered 2000 meters off the coast of California, but only this year scientists have confirmed that it is carnivorous. Similar in shape to a chandelier, it stretches along the bottom to increase in size. It catches small crustaceans with tiny Velcro-like hooks and then stretches a membrane over them, slowly digesting them with chemicals. In addition to all his oddities, he also reproduces in a special way - "sperm bags" - see these balls at the end of each process? Yes, these are packets of spermatophores, and from time to time they swim away to find another sponge and multiply.7. Fish of the Cynogloss family or Tonguefish (Tonguefish)
This beauty is one of the species of tonguefish that are commonly found in shallow estuaries or tropical oceans. This specimen lives in deep waters, and was fished from the bottom earlier this year in the western part Pacific Ocean. Interestingly, some tonguefish have been seen near hydrothermal vents spewing sulfur, but scientists have not yet figured out the mechanism that allows this species to survive in such conditions. Like all bottom tongue fish, both of its eyes are located on the same side of the head. But unlike other members of this family, his eyes look like sticker eyes or scarecrow eyes.6. Goblin Shark or Goblin Shark
The goblin shark is a truly strange creature. In 1985, it was discovered in the waters off the east coast of Australia. In 2003, more than a hundred individuals were caught in northeastern Taiwan (reportedly after an earthquake). However, apart from sporadic sightings of this nature, little is known about this unique shark. This is a deep-sea, slow-moving species that can grow up to 3.8 meters in length (or even more - 3.8 is the largest of those that caught the eye of man). Like other sharks, the goblin shark can sense animals with its electro-sensing organs, and has several rows of teeth. But unlike other sharks, the goblin shark has both teeth adapted for catching prey and teeth adapted for cracking crustacean shells.If you are interested to see how she catches prey with this mouth of hers, here is a video. Imagine that almost 4-meter shark rushes at you with such jaws. Thank God they (usually) live so deep!
5. Soft-bodied Whalefish (Flabby Whalefish)
This brightly colored individual (why do you need bright colors when colors are useless if you live where light cannot penetrate) is a member of the ill-named "soft-bodied whale-like fish" species. This specimen was caught off the east coast of New Zealand, at a depth of more than 2 kilometers. In the lower part of the ocean, in the bottom waters, they did not expect to find many fish - and in fact it turned out that the soft-bodied whale-like fish did not have many neighbors. This family of fish lives at a depth of 3,500 meters, they have small eyes that are actually completely useless given their habitat, but they have a phenomenally developed lateral line that helps them feel the vibration of the water.This species also does not have ribs, which is probably why the fish of this species look “soft-bodied”.
4. Grimpoteuthys (Dumbo Octopus)
The first mention of Grimpoteuthys appeared in 1999, and then, in 2009, it was filmed. These cute animals (for octopuses, anyway) can live up to 7,000 meters below the surface, making them the deepest-dwelling species of octopus known to science. This genus of animals, so named because of the flaps on either side of the bell-shaped head of its representatives and never seeing sunlight, may number as many as 37 species. Grimpoteuthis can hover above the bottom with a jet propulsion based on a siphon-type contraption. At the bottom, grimpoteuthys feeds on snails, mollusks, crustaceans and crustaceans that live there.3. Hellish vampire (Vampire Squid)
Hellish vampire (Vampyroteuthis infernalis name literally translated as: vampire squid from hell) is more beautiful than terrible. Although this species of squid does not live at the same depth as the squid that ranks first on this list, it still lives quite deep, or rather, at a depth of 600-900 meters, which is much deeper than the habitat of ordinary squids. There is some sunlight in the upper layers of its habitat, so it has evolved the largest eyes (in proportion to its body, of course) than any other animal in the world in order to capture as much light as possible. But what is most amazing about this animal is its defense mechanisms. In the dark depths where he lives, he releases a bioluminescent "ink" that blinds and confuses other animals as he swims away. It works amazingly well just when the waters are not lit. He can usually emit a bluish light which, when viewed from below, helps him disguise himself, but if he is seen, he turns inside out and wraps himself in his black-colored robe... and disappears.2. Black East Pacific chimera (Eastern Pacific Black Ghost Shark)
Found in deep water off the coast of California in 2009, this enigmatic shark belongs to a group of animals known as chimeras, which may be the oldest group of fish alive today. Some believe that these animals, separated from the genus of sharks about 400 million years ago, survived only because they live at such great depths. This particular species of shark uses its fins to “fly” through the water column, and the males have a pointed, bat-like, retractable sex organ that protrudes from its forehead. Most likely it is used to stimulate the female or draw her closer, but very little is known about this species, so its exact purpose is unknown.1. Colossal squid (Colossal Squid)
The colossal squid really deserves its name, having a length of 12-14 meters, which is comparable to the length of a bus. It was first "discovered" in 1925 - but only its tentacles were found in the belly of the sperm whale. The first intact specimen was found near the surface in 2003. In 2007, the largest known specimen, 10 meters long, was caught in the Antarctic waters of the Ross Sea and is currently on display at the National Museum of New Zealand. The squid is believed to be a slow ambush predator, feeding on large fish and other squid attracted by its bioluminescence. The scariest fact known about this species is that sperm whales have been found to have scars left by the curved hooks of the colossal squid's tentacles.+ Bonus
Cascade Creature
A strange new species of deep-sea jellyfish? Or maybe a floating whale placenta or a piece of garbage? Until the beginning of this year, no one knew the answer to this question. Heated discussions about this creature began after this video was posted on YouTube - but, marine biologists have identified this creature as a species of jellyfish known as Deepstaria enigmatica.Assignments - simulator on the theme of algae
Preparation for the exam biology.
1. Algae, unlike plants of other groups,
1. do not form germ cells
2. Consist of a variety of fabrics
3. have small size and live in water
4. do not have differentiated tissues and organs
2. Why chlorella and spirogyra are classified as algae
1. they live in the aquatic environment
2. in the process of life, they interact with the environment
3. photosynthesis occurs in their cells
4. their body is not differentiated into tissues and organs
3. What plant is classified as algae
1. chlamydomonas
3. arrowhead
4. What plants are algae
1. to the lowest
2. to higher
5. The body of chlamydomonas and chlorella algae is represented by:
1. thallus, not divided into absorbing and photosynthesizing parts
2. thallus with rhizoids
3. thallus without rhizoids
4. single cell
6. Conductive tissues are absent in:
1. club mosses
2. algae
3. ferns
4. flowering plants
7. Which of the listed groups of plants do not belong to the higher
8. Plants consisting of one cell or many cells that are not differentiated into tissues are classified as
2. algae
3. lichen
9. The interaction of fungus and algae in lichens is an example
1. predation
2. competition
3. symbiosis
4. Variability
10. Which of the algae are able to live at a depth of up to 200 m?
1. green
3. red
4. all of the above
11. In green algae, chlorophyll is found in:
1. cytoplasm
2. chloroplasts
3. chromatophore
4. Vacuoles
12. Multicellular algae are attached to the bottom with:
2. rhizomes
3. rhizoids
4. Thallus
13. The body of algae consists of:
1. root and shoot
2. thallus and rhizoids
3. stem and leaves
4. Mycelium
14. The reaction to light in chlamydomonas is carried out with the help of:
2. vacuoles
3. chromatophore
15. Algae absorb water and minerals:
1. rhizoids
2. leaves
3. roots
4. whole body
16. In chromatophores in the light is formed:
1. chlorophyll
3. agar-agar
17. K asexual reproduction unicellular algae is :
1. cell division of unicellular algae
2. reproduction by spores
3. reproduction by body fragments
4. all of the above ways
18. What phase of the life of ulotrix is diploid
1. green thread
2. zoospore
19. Of these plants, algae is:
3. seaweed
4. water lily
A) Chlamydomonas
B) Chlorella
1) has a photosensitive eye
2) flagella are absent
3) heterotrophic nutrition is possible
4) moves actively
5) reproduces with the help of zoospores
6) reproduction is only asexual
20. Taxon red algae has a rank:
a) kingdoms
22. In plants, gametes are formed:
b) department;
a) as a result of mitosis on the gametophyte;
23. The organs of sexual reproduction of plants are:
24. Multicellular green algae include:
c) class;
a) sporangia and gametangia;
b) as a result of meiosis on the gametophyte;
25. Brown algae include
a) cladophora;
26. Algae from which agar-agar is extracted:
b) gametes (eggs and spermatozoa);
d) order
28. Algae that can live at very great depths:
b) volvox;
27. Seaweeds accumulate in their body:
c) as a result of mitosis on a sporophyte;
a) kelp, ulotrix;
a) red
a) green
29. Closer to the surface of the water live:
a) carbon dioxide
b) green;
c) spirogyra;
b) fucus, chlamydomonas;
d) as a result of meiosis on the sporophyte
c) rhizoids;
c) spirogyra, cladophore;
d) antheridia and archegonia
a) red algae;
d) chlorella
d) kelp, fucus
b) green algae;
c) red;
c) oxygen;
d) all algae
c) brown algae;
d) all named
d) all of these algae
30. Chlorella differs from chlamydomonas in that:
a) it does not have a chromatophore;
31. Chlorella is specially grown because
32. Photosynthesis in algae occurs:
b) it does not have flagella;
a) contains many vitamins and proteins;
33. Rhizoids are:
a) in chloroplasts;
c) it does not form a dispute;
b) rich in fats and carbohydrates;
a) filamentous algae;
35. In chromatophores in the light is formed
b) in stigma (photosensitive eye);
36. Signs characteristic of algae:
b) root-like outgrowths;
c) feeds on bacteria, purifying the air;
d) it produces less organic matter
c) in a sheet;
37. Algae belong to the plant kingdom, because:
a) chlorophyll;
37. Laminaria, purple, spirogyra - representatives:
a) the presence of a variety of tissues;
a) they have a cellular structure;
38. The role of algae in the life of a reservoir:
a) one department of algae;
b) absence of tissues and organs;
d) breeds well in water
c) leaf-shaped plates;
d) in the chromatophore
d) stem-like formations
b) three divisions of algae;
c) agar-agar;
b) in the process of life they interact with the environment;
c) developed root system;
a) contribute to the purification of water;
b) enrich water with oxygen and accumulate organic matter;
c) chloroplasts are located in their cells;
c) three classes of algae;
d) lack of roots and the presence of rhizoids
d) higher plants
c) use organic substances in the process of respiration;
d) their cells breathe
d) contribute to the overgrowth of the reservoir
Single-celled green algae - chlamydomonas as a representative of the plant kingdom has
cell wall containing chitin
cell wall containing fiber
chromatophore containing chlorophyll
unenveloped nuclear contents in the cytoplasm
storage material starch
DNA closed in a ring
Find three errors in the given text. Indicate the numbers of sentences in which errors were made, correct them. 1. Algae is a group lower plants living in the aquatic environment. 2. They do not have organs, but there are tissues: integumentary, photosynthetic and educational. 3. Single-celled algae carry out both photosynthesis and chemosynthesis. 4. In the development cycle of algae, there is an alternation of sexual and asexual generations. 5. During sexual reproduction, the gametes fuse, fertilization occurs, as a result of which the gametophyte develops. 6. In aquatic ecosystems, algae perform the function of producers.
2. Algae do not have organs and tissues. 3. Chemosynthesis occurs only in bacteria. 5. When gametes merge in plants, a sporophyte is formed.
Laminaria contains a large number of iodine, which is necessary for the production of thyroxine, a thyroid hormone.
Red algae (crimson) live at great depths. Despite this, photosynthesis occurs in their cells. Explain how photosynthesis occurs if the water column absorbs the rays of the red-orange part of the spectrum.
In addition to chlorophyll, red algae contain other pigments - carotenoids, which absorb blue-violet light, and phycobilins, which absorb yellow-green light.
Why do plants with a green color live on the surface of water bodies, and red in the depths of the sea?
Plants with a green color in the process of photosynthesis absorb light in the red part of the spectrum. Water does not transmit such light well, only green and blue rays remain at a depth, red pigments are required to absorb them.
How do substances move in multicellular algae in the absence of a conducting system?
Substances move along the thallus from one cell to another by diffusion.
After reading the question, I could think on the wave of associations about the ocean, about documentaries about nature, about strange deep-sea animals, but in this moment in my head SpongeBob with a net catches pink jellyfish.
Well, it happens. But I still have something to tell about the inhabitants of the seabed.
The bottom of the ocean and what are the conditions there
With increasing depth, the ocean becomes less and less suitable for life, because the farther from the surface, the less sunlight becomes (it does not reach the bottom layers of the ocean at all), the temperature decreases more and more and the pressure increases (of course - under such a water column!).
It is precisely because of the lack of sunlight that there are no plants that need it for photosynthesis.
However, it cannot be said that there is no light at all at the bottom of the ocean. Some deep sea organisms are capable of bioluminescence, i.e. they themselves partially or completely glow.
I’ll also add from natural tediousness that it’s not entirely correct to say that at great depths there are only animals, because in addition to animals and plants there are other kingdoms. All sorts of fungi, bacteria and other small organisms. There are definitely bacteria at the bottom of the ocean, although I don’t know so much about them - animals interest me more.
Animals of the Deep
Animals of different groups live at the bottom of the ocean:
- fish;
- echinoderms;
- crustaceans;
- various shellfish;
- worms.
Of particular interest are deep-sea fish species, which often look, to put it mildly, unusual.
Sea devils (anglers) are typical representatives of the deep-sea fauna.
Or here are the famous flounders, which have eyes on one side of the body, and they swim lying on their side.
Deep-sea sharks look quite strange, although they are recognizable as sharks. At greater depths, species such as the frilled shark and the Brazilian glowing shark live.
By the way, there are also glowing anchovies. Bioluminescence is always cool.
By the way, despite the absence of plants, not all inhabitants of the depths are predators. Some deep-sea organisms feed on carrion, zooplankton, or detritus.
