What do anemones from the Dead Sea look like

Are sea anemones plants or animals?

When you see sea anemones, the image of the flower inevitably comes to mind. Her tentacles sway in the current in all colors, delicate and fragile. But the beings belonging to the flower animals are clearly animals. There are around 1,000 species worldwide, from the beach to the depths of the oceans, from the South Seas to the poles. Even if they are not flowers, quite a number of them feed on sunlight with the help of stored unicellular algae, just like their close relatives, the corals. Many of the bright colors also come from these algae.

Even the impression that anemones don't move is deceptive. Their adhesive disc, with which they hold themselves to the ground, is muscular. With her they crawl slowly but steadily across the floor. They do this especially when the current no longer drives enough food into their arms. Once they have made a catch, they put it in their mouth, which is in the circle of their arms, with elegant movements. By the way, you shouldn't get too close to most of the beauties. Like jellyfish, they belong to the cnidarians and leave painful traces when touched.
Why was there never an oil spill after a seaquake?
Heiko Kusatz, by email

"Most offshore deposits and exploration areas are located on tectonically calm, so-called passive continental margins," says Dr. Dieter Franke from the Federal Institute for Geosciences and Natural Resources. "This is why there are no significant seaquakes in the Gulf of Mexico, Brazil, West Africa, China or Australia." Exploratory drillings are also drilled on active continental margins, i.e. those at risk of earthquakes, such as Nicaragua or Sumatra. However, the potential deposits there are quite far from the earthquake zones. In addition, the epicentres of the strong earthquakes lie at relatively great depths below the deposits. "Only if the ocean crust were to tear open from the seabed to the reservoir in the course of an earthquake could oil spills occur." Nevertheless, natural oil leaks on the seabed are observed in the Gulf of Mexico and the Black Sea. The reason for this are submarine salt domes that cause cracks and fissures. It is estimated that there are around a thousand natural springs in the Gulf of Mexico, with up to 200 tons of oil leaking daily. The spots this causes on the sea surface can even be seen on satellite images.

Would it be ecologically justifiable if everyone were burned to death and the ashes thrown into the sea?
Question from the mare editorial team

How many people are currently buried at sea, there are no exact figures, says Alexander Helbach from the Aeternitas association. The consumer initiative for funeral culture assumes, however, that there are between 10,000 and 20,000 - about two percent of all deceased in Germany. The burial industry has been discussing the dangers burials can have for nature, since the increasing number of burial forests has been in demand as grave sites. "Many pollutants in human bodies evaporate when they are burned," explains Helbach. How much of it and to what extent can still be detected in the ashes has only been insufficiently researched. Incidentally, it is not the case that the ash simply spreads in the water, says Helbach. "The special urn sinks and dissolves, the ashes form a pile on the ground and slowly spread over time."

Do seafarers actually have a preference for burial at sea?
Emil Schuschnig, Eichenau

Burials at sea have been common in Germany for around 35 years. From Borkum to Sylt, from the Flensburg Fjord to the Greifswalder Bodden, around 5,000 people find their final resting place at sea every year. A number of shipping companies offer their services for this. According to the Federal Association of German Undertakers, people who opt for this form of burial usually have a personal connection to water. Be it because they were sailors and anglers or boat drivers and inland waterwaymen. "This slope to the sea is not only found on the coasts," says Ralf Paulsen from the German Sea Funeral Association. “We also receive inquiries from southern Germany; for example of people who have lost relatives at sea and want to feel united with their loved ones after their own death through a funeral at sea. ”Since the funeral directors rarely have information on the professional backgrounds of the dead and no corresponding statistics are kept, it is uncertain whether ship officers or mechanics, ie seafarers in the sense of the current job descriptions, prefer to be buried in the sea.
Is it true that seaweed was used to fill the mattress?
Katja Böttger, Bremen

In the past, when latex, foam and innerspring did not yet determine the inner workings of a mattress, it was common practice on the coast to fill mattresses with seaweed. Submerged in water up to several meters deep, extensive stocks of common and dwarf seaweed thrived on the North and Baltic Seas. When severe storms raged, the plant's long and very narrow leaves were washed up in large quantities on beaches and coasts. They only needed to be collected and dried. As a filler for mattresses, seaweed had many advantages: It was easy to work with and insulated against the cold. In addition, the high salt content acted as fire protection and kept mold and insects away. Fungal infestation and increasing pollution contributed from around 1930 to the fact that the seagrass stocks declined badly. Nevertheless, seaweed was used as upholstery for armchairs and sofas until the 1960s. Today, upholsterers rarely have to deal with the aquatic plant: mostly when older people bring their family heirlooms to reconditioning.
Why do some sea urchins cover themselves with materials lying around on the sea floor, but others do not?
Helmut Braun, Ortisei

Despite their spines, sea urchins are a popular snack for many fish. In order to avoid this fate, the sea urchins have developed counter-strategies. They cover themselves with algae, remains of mussels or other materials lying around on the sea floor.

The spiny animals are closely related to the starfish. Like these, they have suction cups, which are, however, much longer. Some species even have suction cups on the top of their calcareous shells. Members of these species can use it to pick up material from the sea floor and balance it using their spines. Tests have shown that "protected" specimens do not end up in the belly of the next best predatory fish as quickly as they are harder to eat. While the benefits are obvious, not all sea urchins that might get themselves shields. It is crucial that sufficient suitable materials are available.
If this is the case, then all animals are well guarded.

Sea urchin - Aristotle's lantern

Why is the jaw of the sea urchin called "Aristotle's Lantern"?
Helmut Braun, Ortisei

Aristotle, the Greek philosopher and polymath, first described the structure of the jaw skeleton in sea urchins and compared it to a lantern. In his honor, Pliny later coined the term "Aristotle's Lantern". The name is correct: The complicated, five-sided structure looks like a lantern that was common at the time and tapered to a point. All echinoderms, which also include the sea urchins, are difficult or impossible to divide into right and left. So they do not have a two-sided bilateral, but a five-sided symmetry. The starfish show this particularly well. The sea urchin jaw is structured accordingly. In total there are about 40 elements that are closely interlocked to enable the sea urchins to bite powerfully. With this precision instrument, the approximately 1,000 species of sea urchins scrape algae from rocks, nibble on sponges and eat worms, mollusks and some corals. Others even drill holes in stones. So it's no wonder that your teeth are constantly growing back - up to 0.2 millimeters a day. Wearing takes place at predetermined breaking points, which are designed in such a way that the teeth always remain sharp and therefore ready for use.
How do sea urchins reproduce?
Hermine Ulrich, St. Moritz

Even if you can't see it, there are also males and females in sea urchins. However, like most invertebrates, they do not come too close when mating, but release eggs and seeds freely into the water - perhaps better, given their prickly nature. Some sea urchin species gather in groups of 10 to 30 animals during the mating season. This increases the likelihood that the seed will meet the egg. In addition, the egg releases attractants, which the sperm follow. After fertilization, the egg develops into a larva that floats freely through the oceans for one to several months before the mini-sea urchin finds its home on the sea floor.

Echinoderms, which in addition to sea urchins also include starfish, sea cucumbers, hair stars, feather stars and brittle stars, all have a more or less five-pointed symmetry in the adult stage. But their larvae have the normal bilateral symmetry that all other animals have. Sea urchins become sexually mature - depending on the species - after two to five years and can reproduce well into old age. After all, red sea urchins can live up to 200 years. These methusalemes even produce more and better sperm and egg cells than the younger ones.
How does a sea urchin petrify?

If the strange pebble on the beach turns out to be a petrified sea urchin, the joy is great. Sea urchins have a good chance of ending up in a fossil collector's showcase because they have a hard, calcareous shell and live in the sea. There they are more quickly covered by mud than on land. This protects against scavengers and putrefaction. Only a tiny part of all remains of living things fossilized. Sometimes a sea urchin shell fills up with sea mud. Over the course of millions of years, it petrifies due to the pressure of the layers deposited on it - a stone core is created. As printed, it depicts the inside of the sea urchin shell. The shell itself usually dissolves. But if its crystal structure changes, it can also be preserved.

Whether the stone core, imprint in the surrounding rock or shell survive depends on the circumstances. Nobody knows exactly how long it will take for a fossil to form. But if a fish fossil shows even details of the filigree gills, the fish must have been surrounded by a protective shell within hours.