All the best wishes for these holidays and for every day of the year 2025 that will soon begin.
Every moment, every tiny space around us contains an entire unfathomable universe, in which beauty beats and peeks through the fine cracks of our senses...
Trying to discover what reaches us is something exciting that we try to capture here in brief brushstrokes.
Thank you for your company.
HAPPY 2025 !!
::::::::::::::::::::::::::::::::::::::::::::
In
Biodiversidad virtual and also on Instagram as @proyectoagua.
In its very heart of crystal and gelatin,
Acantholithium keeps the rose of the winds and the seas, attached to the pins to which its fragile body is tied.
It marks with its arms all the constellations in the sky and points out underwater the unfathomable mysteries of the abysses, hinting at more than a dozen cardinal points.
Today, with rainbow lights, its celestine skeleton became a star, which among the waves of the waves points out the unknown directions of the invisible.
The acantharia (Acantharia) constitute a group of marine and planktonic protists that are included within the radiolarians. The main peculiarity that makes them unique among all living beings is that they have a skeleton composed of celestite crystals (strontium sulfate), which ends up dissolving in water.
Acantharia are always active predators, and although many of them associate in symbiosis with small green algae, they capture small organisms with the help of their fine, radiating thread-like hands, the axopodia. Acantharia currently includes about 50 genera and 150 species.
The skeleton of the acantharia is composed of twenty radial spicules (ten diametrical), more or less joined at the center of the cell in very different ways. The arrangement of the spicules is very precise and is determined by constant patterns of symmetry in this group.
The way in which the spicules join together at the center of the cell varies according to species and this is one of the primary characteristics used in the taxonomy of the group. In some species the spicules only cross at the center of the cell, while in others they fuse there giving rise to star shapes like those of today.
The cytoplasm in these organisms is organized into two well-differentiated portions, a denser endoplasm in the central part and a peripheral zone of ectoplasm separated by the central capsule. The endoplasm contains the nuclei and a large number of other cellular organelles: Golgi apparatus, endoplasmic reticulum, mitochondria, ribosomes and others.
The central capsule containing the endoplasm is composed of microfibrils organized in twenty plates, each of which has an orifice through which a spicule projects, while the peripheral ectoplasm contains the digestive vacuoles and often has zooxanthellae and other symbiotic algae. Surrounding the ectoplasm is a cortex of microscopic fibers linked to the spicules by fibers called myonemes. These help with flotation, along with the vacuoles of the ectoplasm.
The number of axopodia is fixed in each species, with adult individuals almost always being multinucleate. Reproduction is carried out by the formation of swimming cells that can be flagellated. Not all stages of the life cycle of these organisms have been observed, and their study is hampered by the impossibility of maintaining these organisms in culture.
Acantholithium appears to be a cosmopolitan, although uncommon, genus, and like other acantharians of similar morphology, it can be affected by disturbances caused by wind or rain, which causes them to rapidly descend to the deepest areas, from where they return to the surface once the appropriate conditions have been reestablished.
Acantholithium stellatum has fine pyramidal-shaped spicules with 4 lamellae each, surrounded by 8 myonemes and a finely granulated ectoplasm containing 6 to 8 zooxanthellae.
Almost all species in this group have a tropical and/or subtropical distribution, while the number of those inhabiting cold-temperate waters is comparatively low, probably around 10-20% of the total, although most of their records in colder waters are associated with the influence of warm water currents.
The photographs we show, taken live at 200x magnification using the dark field, phase contrast, interference contrast and polarization technique, have been taken on samples collected on September 26, 2024 in the vicinity of Playa de Grande in Tossa de Mar (Gerona)
