🌊✨️ At the beach of Baltrum, the sea washed up the delicate skeleton of Echinocardium cordatum, a heart urchin. Its sharp spines are gone, leaving only the pale, fragile shell with fine patterns.

🫧🤍 The heart urchin lives under the sea, buried in soft sand or mud, up to 15 centimeters deep. It uses its small spines to dig and feeds by filtering tiny food particles like the decomposing remains of organisms and plants (detritus) from the sand around it.

👽🪸 Sea urchins may look very alien at first glance, yet they are actually more closely related to us humans than to snails or insects. This is because sea urchins – just like starfish – belong to the echinoderms.

🪞🤔 If you only look at their appearance, you might think: Wait a minute! Starfish and sea urchins look nothing like most animals. Many animals – including humans – have two mirror-image halves (bilateral symmetry). Echinoderms, however, are radially symmetrical, usually with five identical sections. That might make it seem like they’re even less related to us than snails or insects, which also have two symmetrical sides.

🧬🔬 But appearances can be misleading. Echinoderms, like all vertebrates, belong to the deuterostomes. Snails and insects, on the other hand, are part of the protostomes. A key clue: echinoderms are bilaterally symmetrical in their larval stage. It’s only later in life that they develop their characteristic radial symmetry.

👄♻️ The fundamental difference between protostomes and deuterostomes shows up very early in embryonic development: in deuterostomes, the first body opening (the blastopore) becomes the anus, and the mouth forms later. In protostomes, it’s the other way around – the blastopore develops into the mouth.

🤗 For a more nuanced discussion, please feel free to use the comments section, private messages or the anonymous contact form on my website.

🪸 In my hand, I’m holding a piece of bladderwrack (Fucus vesiculosus), a seaweed commonly found along the Wadden Sea coast. The small, round bladders are not fruits but flotation organs. They help the seaweed stand upright in the water so its flat fronds can catch as much sunlight as possible. This is essential for photosynthesis – the process of turning light energy into nutrients.

🌊🫧 The bladders are filled with a mixture of gases. This is mainly oxygen, which the seaweed produces during photosynthesis, and nitrogen, which diffuses in from the surrounding seawater. Carbon dioxide, which the seaweed needs to grow, is almost absent because it is used up immediately. Thanks to this high oxygen content, the bladders provide enough buoyancy to keep the seaweed floating, allowing it to capture as much light as possible even at high tide or in murky waters.

🧫🔬 From a biological point of view, Fucus vesiculosus is a brown alga. It belongs to a group called the Fucales within the family Fucaceae. Even though it looks like a plant and makes its own food through photosynthesis, it is classified in a broader group called Stramenopiles, which also includes diatoms (tiny plankton) and some organisms that don’t photosynthesise at all. How exactly brown algae fit into the tree of life is still being studied, and researchers continue to discuss their relationship to other algae and to the ancestors of land plants.

🤗 For a more nuanced discussion, please feel free to use the comments section, private messages or the anonymous contact form on my website.

🤔 What do you think I’m holding in my hand?

🔍 If you’re thinking of a seaweed, you’re already halfway there! But apart from its branching structure, there’s not much of the seaweed left to see. That’s because it has been colonized and completely covered by a colony of tiny animals! These are moss animals (bryozoans), more specifically Electra pilosa.

🏘🦠 Moss animals usually form colonies (zoaria) made up of many individual animals (zooids). Each zooid consists of a soft body and a protective shell.

🪸🤝🪸 Within colonies, there is a division of labor. Strongly reduced individuals form stalk segments, tendrils, or root-like filaments. Other zooids produce reproductive cells – still others become "nurse" zooids or develop into bird’s-head-shaped avicularia or vibracularia, which prevent other organisms from settling on the colony. In these specialized zooids, both the tentacle crown and usually the gut are reduced.

🏡🦠 In short: the seaweed is mainly just living space for Electra pilosa, not a partner. For the seaweed itself, it is usually more of a burden than a benefit.

⛴️🪸 Moss animals can cause damage or maintenance costs to ships, harbor structures, and water management facilities through heavy growth.

💉🧫 On the other hand, they produce chemical compounds that are the subject of medical research, including the potential anti-cancer agent bryostatin 1.

🤗 For a more nuanced discussion, please feel free to use the comments section, private messages or the anonymous contact form on my website.

🦪🐌 Mollusks on Baltrum

🌊 On the beach of Baltrum, you can find many shells of mussels and snails from various species. These accumulations of washed-up shells — a phenomenon known in German as Schill — are a common sight along the shoreline. When swimming in the North Sea, you often have to cross a layer of these sharp shells before the water is deep enough to swim (I did it despite the low temperatures in May).

🦪 Here we see Atlantic jackknife clam (Ensis leei), common cockles (Cerastoderma edule), prickly cockles (Acanthocardia echinata), and many other species.

🦪 In the second picture, I’m holding a European flat oyster (Ostrea edulis) in my hand. Mussels play an important role in cleaning the oceans, as they filter pollutants from the water. They also form mussel beds, which serve as habitats and function similarly to coral reefs.

🐚 In the third picture, there is an old common whelk shell (Buccinum undatum). These are relatively rare to find because their populations have declined and because hermit crabs prefer exactly this type of shell, often taking them before they can be washed ashore.

🐌 At the groynes – that's the name for the wave breakers made of wooden posts and stones – you can find the common periwinkle (Littorina littorea). In the photo it's on a wooden post, in the video on a stone groyne.

🐌 There are also land snails on Baltrum. I saw the garden banded snail (Cepaea hortensis, on the rose) and the grove snail (Cepaea nemoralis, on the paved path). You can tell them apart by the lip of the shell: Cepaea hortensis has a light edge at the shell opening, while Cepaea nemoralis has a dark one.

🤪 In the last picture, I show you a land slug (Arion species) cheekily smiling into the camera.

🤗 For a more nuanced discussion, please feel free to use the comments section, private messages or the anonymous contact form on my website.

🌊 Haven of Serenity

🏝 The sloths were generated with FLUX AI. The environment and some sloth details were created with Adobe Firefly. I spent quite a long time on it. I wanted it to be completely AI generated and that doesn't always do what it's supposed to.

🏗 Originally, when I generated it with FLUX, the sloths were in a kind of metal container in a mechanical setting. I gave the image some longing, warmth and fantasy, but also subtle contrasts.

Initial prompts: FLUX AI
Enhancement: Adobe Firefly AI

🤗 For a more nuanced discussion, please feel free to use the comments section, private messages or the anonymous contact form on my website.

September heatwave 🌡️🔥🌊🌞

The beginning of autumn was only pretended.
Now it's back to ice cream and tropical nights.

🤗 For a more nuanced discussion, please feel free to use the comments section, private messages or the anonymous contact form on my website.