The oceans are home to innumerable creatures, from minute bacteria to the mighty blue whale. Amid this, there are various unicellular organisms which exist. These organisms have a single cell, which contaians the DNA, cytoplasm and organelles required for survival.
All major life processes like respiration, digestion and reproduction are carried out within the single cell. There are mainly two categories -- prokaryotic and eukaryotic. The difference between the two is that prokaryotic organisms lack a nucleus, while eukaryotic organisms have one.
These organisms can survive in a broad range of environments. Algae is a eukaryotic organism, and one of the unique types found in the oceans is the ‘Valonia Ventricosa’, also known as bubble algae or Sailor’s eyeballs. Its appearance stands out with distinct biological features.
The most notable characteristic are large, spherical, bubble-like cells, which can grow up to 10 cm in diameter. Not only are they visually appealing, but are important for the algae’s survival. Now, each of these large bubbles is filled with a single large vacuole, which stores water and other substances, enabling the algae to float on the surface. These bubbles are made of thin, flexible cell walls, formulated of cellulose. The membranes do not seem to have aquaporins, or pores for letting the water go. Each of these bubbles are capable of dividing to form new bubbles, forming colonies of interconnected spheres. Unlike plants, they do not have roots, stems or leaves. Instead, these cells are organised in a single layer, along with a thin film of chloroplasts that photosynthesise. These chloroplasts are the reason behind the green colour.
Although these bubbles appear to be fragile, they can survive extreme environmental conditions, from shallow waters to deeper zones of the ocean. They can be found growing on rocks, coral reefs, and seagrasses. These organisms exist in the world’s tropical and subtropical oceans. These algae prefer to grow in areas of moderate water movement, usually growing on coral reefs, rocky shores and seagrass beds.
Valonia Ventricosa plays a critical ecological role in its habitat, especially in the coral reef ecosystems. Not only do they provide oxygen for various marine species, but offer shade and refuge for predators.
They also play a prominent role in stabilising the structure of the seafloor or coral reefs. These structures can shape into thick mats, and they avoid erosion by buffering against strong wave action. Besides, they help in nutrient recycling, as the decayed algae releases essential nutrients in the water.
Despite this, they also have a negative impact on the ecosystem. When present excessively, they can outcompete other organisms for nutrients and space. They can smother coral reefs, curbing the growth of other organisms. The reproduction of these organisms is primarily asexual. A single, large bubble cell divides to form smaller bubbles, which can either remain connected to the parent colony, or drift to form new colonies.
This method allows for fast growth and expansion of these organisms. There are few instances where there is sexual reproduction too, where two bubbles come together and exchange gametes. Post fertilisation, the zygote forms a new bubble, and this cycle repeats in a loop. However, this reproduction happens when there is environmental change, like periods of nutrient stress or switching in light levels. The first description of these unique organisms dates back to the 19th century. These remarkable organisms have been used in various scientific studies. They have helped in discerning cell biology, photosynthesis and marine ecology. It has also helped us understand the functioning of single-cell organisms and how they interact with the environment.