Algae are one of the first biological groups on Earth, and after continuous evolution, their growth territory has gradually expanded. From seawater to estuaries and from estuaries into rivers or freshwater lakes. Some of the most resilient species have even become the most common species in lakes.
<h1>Dangerous journey</h1>
Coccidioid travel is not simple. From the moment it leaves the embrace of the warm ocean, it embarks on a dangerous and arduous journey, no less difficult than the human landing on Mars. The difference in the properties of freshwater and seawater reduces the solubility of inorganic carbon, making it more energy to obtain the raw materials needed for photosynthesis; even if it is accidentally exposed to fresh water, there is a risk of cells bursting due to unbalanced osmotic pressure.
In addition, the concentration of sodium ions in fresh water is low, and many nutrient salt absorption mechanisms that rely on sodium ion regulation will be out of balance. Therefore, the first challenge facing coccidioides is how to squeeze excess water out of the cells, and then adjust their nutrient salt intake mechanism to make life not afraid of scarcity.
<h1>Scientific evidence</h1>
The Baltic Sea was once a salt sea, and the seawater from the North Sea would flow into the sea through the passage; after the Ice Age, the channel was reduced, and the baltic sea salt content was greatly reduced due to the decrease in the inflow of the North Sea water, and a stable salt gradient was also produced from south to north. In the north of the Baltic Sea, only 0.5% of the water's salt remains. 1 salinity (pus); there, apart from the small bubble horn algae, there is almost no other seaweed. Scientists have found that there are two main reasons for the decrease in the reproduction rate of seaweed: the motility of gametophytes (sperm and eggs of algae) is reduced, and the life span is shortened, which greatly reduces the chance of pairing sperm and eggs; even if sperm and eggs have a way to meet, the rate of fertilization of multiple sperm is also high.
Why can the unique little bubble horn algae grow here? Scientists took the small bubble ink horn algae growing in the North Sea, the Central Baltic Sea, the North Baltic Sea and the estuary for comparison, and found that the population growing in the North Baltic Sea, in addition to the egg release rate is 4 times higher than that of sperm, after the egg is fertilized, the membrane potential is maintained at a high potential for a long time, which is enough to reduce the chance of other sperm combining again and improve the success rate of fertilization. Little bubble horn algae is really lucky. Because of this special ethnic group, it did not disappear from the northern Baltic Sea during this environmental change.
<h1>Propagation strategies of red algae</h1>
Like many higher plants and animals, sexual reproduction and asexual reproduction alternate repeatedly over the course of most red algae's life. In order to cope with changes in the environment and increase the number of offspring, the reproduction methods of red algae are dazzling. What's even more surprising is that they all seem to be familiar with a variety of strategies. More than once, scientists have found that the number of individuals who adopt asexual or sexual reproduction in different environments varies greatly, and that asexual reproduction seems to have a tendency to replace sexual reproduction when the population is insufficient. All of these workarounds are the evolution of water by living things over time. Scientist Staceys believes that "there are countless secrets in various reproductive strategies, and if we carefully observe their circulation and changes, we have the opportunity to fully understand living things." "Let's learn about this interesting topic.
<h1>sexual reproduction</h1>
There are fertilized hairs at the tip of the female gametophyte of the fairy cabbage, and the sperm slides through the small hole at its apex and binds to the egg cells at the bottom of it. After the female gametogene is fertilized, it will develop into a sporangia, and when the fruit spores inside are mature, they will disperse and become sporophytes.
The production of tetraspores is an important process of red algae from sporophytes to gametophytes. Sporophyte cells with two sets of chromosomes produce tetraspores containing a single set of chromosomes through meiosis. Tetraspores mature from sporangia and subsequently develop into female and male gametophytes. The proportion of distribution will vary depending on the environment.
<h1>agamogenesis</h1>
On the petioles of aquatic plants, the thick black short hairs are a freshwater red algae, which we call the arbuscular Odhu algae. It has two asexual reproductive strategies, one is creeping reproduction, which crawls through the entire petiole through creeping silk; the other is propagated by monospores. The tip of the finger-like short branch hanging from the branch, an oval globule dyed dark purple by the dye, is a single spore. When the single spores mature, they will break away from the mother branch and drift away with the current of water, increasing the breeding space of the population.
<h1>Algae also have sex hormones</h1>
Compared with red algae, the reproductive strategy of brown algae may be relatively flexible. Both their female and male gametes have flagella and are free to move around in the water, finding new living spaces to reduce the pressure of competition between the species. In the case of the long-sac water cloud, the female gamete has about 24 hours to look for the implantation point after leaving the mother plant. When it lands smoothly, it will begin to emit sex hormones and guide the male gametes to come and mate. The clever male gamete, in addition to having bright eyes and able to sense light, also has a sensitive nose, which can clearly distinguish whether he is getting farther and farther away from the fragrance or getting closer and closer. Therefore, it is not difficult at all to find a job of "sweetheart". After the male gamete rushes to the female gamete, he will gently fall on her body, and wait for the choice of the female gamete with the other male gametes who have come at the same time. The male gamete selected by the screen of the sparrow screen then completes the marriage with the female gamete and starts a new life.
<h1>It turned out to be small molecules</h1>
All brown algae sex hormones are volatile aromatic compounds with similar chemical structures, and algae similar to brown algae often synthesize the same sex hormones. Amazingly, the odds of xenobreeding in nature are low. Because the process of female and male gametes joining is highly specific; even if they are the same, if they are from a strain that cannot be matched, they cannot complete mating. The purpose is only to ensure that future generations are healthy and healthy, and the survival rate is high.
The sex hormone of the long sac water cloud is ectocarpene. The male gamete is extremely sensitive to it, and the concentration of pheromone molecules is as long as it is higher than 6. 1× 10-13M, you can promote the aggregation of male gametes. In other words, just one molecule per milliliter of seawater is enough to trigger a reaction. After successful mating, it immediately germinates into sporophytes and enters another life process.
A small chemical molecule can lead to a marriage. At this point, I deeply feel that algae are much smarter than us humans in terms of mate selection. Corals aren't the only aquatic creatures that can spawn en masse. In order to fight for living space, the algae on the coral reef also use the same trick; choose a good day, the sperm and eggs are released, and the wedding is completed.
<h1>Witness the wonders of nature</h1>
Thanks to a sturdy young scientist, Cliffordon, who waited patiently at Cape Santa Burros in Panama, he discovered the mystery. At 5:53 a.m. on October 26, 1994, he was very unexpectedly confronted by the spectacular scene of the mass spawning of calcium fan algae off the coast of Panama, which made him determined to devote himself to this interesting research work. By May 12 of the following year, he had seen a total of 38 collective spawnings belonging to 8 species of green algae. For five months from June to November, he dived twice a day (between 5:30 a.m. to 7:00 a.m. and 2:30 a.m. to 4:00 a.m.) in order to watch the green algae spawn more closely, waiting for the green algae to spawn. Finally, emperor Tian lived up to his painstaking efforts, and he recorded this very planned natural wonder.
<h1>The wedding of green algae</h1>
Thousands of individuals, overnight, are ready for hatching. In just 5 to 15 minutes in the early morning of the next day, the mature gametes are released at the same time, and their concentration is so high that the visibility of the seawater can be instantly reduced to less than one meter. After the gamete is released, there is only 40 to 60 minutes to seek pairing. Subsequently, it sinks with the fertilized egg, so that the sea water is cleared again. This dramatic performance, from the preparation of the algae body to breed, to its completion and retirement, is less than a day and a half.
Water temperature and light intensity are two major factors that control collective spawning. The environmental needs of different types of green algae are different, so the gametophytes of various algae can be released without interfering with each other, within 3 hours before and after sunrise, to complete the major event of reproduction.
Isn't nature magical and mysterious? In the darkness, there seems to be a force of integration and organization, so that everything that lives in it does not take a wrong step in the busy process of life.