In others the shell is typically buried in the the mantle or reduced to just calcium crystals, others do completely lack a shell. Secondly, and probably most importantly, “slugs” evolved from molluscs! “Slugs” are not a real taxonomic category as the term slug is given to any shell-less gastropod so slugs are in no way a monophyletic group. Anyways, we call slugs molluscs because they evolved from molluscs! Slugs in most cases (I’m not getting into marine lineages) are descended from snails that eventually lost or had a reduction in their shells.
Finally and this is definitely the most important reason, not all molluscs have shells! The phylum mollusca has multiple classes, which typically united via the presence of a muscular foot or a mantle:
Octopodes lack true shells and there is even a whole class of molluscs that completely lack shells, the aplacophora (which translates to: not plate bearing). Aplacophorans are pretty rare and worm like in form, most species are burrowers and many have calcium spicules embedded in their mantles to provide rigidity.
This is a tough question, and a very big question. Since it’s just about impossible to objectively explain why birds are amazing (they are, btw), maybe I can explain why birds amaze me and why they’re the focus of both my career and a significant portion of my recreational time.
1. Birds are dinosaurs that you can hold today.
Flashback to 2010, a time when little Redstart was thinking about applying to college. For a while I was convinced I would pursue animation and go be some awesome art director of nifty animated films starring animals. Then I realized that a) I wasn’t good enough or motivated enough to make it, and b) having art as a career would ruin creating art for me. So, then it was back to my other passion: paleontology.
I literally applied to college planning to be a geology/biology double major with a long-term career goal of being a professor of paleobiology. I doggedly pursued this game until my sophomore year of college, when I discovered birds.
Birds are dinosaurs. Just about everyone knows this now (thank goodness). The big, significant realization here is that you can study dinosaurs today. Think about the magnificent breadth and depth of scientific questions you can ask about an animal when it’s right in front of you, instead of turned into rock and shattered into a million fragments! Don’t get me wrong; paleontology is an awesome field. But instead of dedicating my life to recreating the world of millions of years ago, I decided to work on unraveling the mysteries of today’s dinosaurs.
2. Birds are Pokémon.
Stay with me, now! As a wee youth I was obsessed with Pokémon. Wait, I’m still obsessed with Pokémon. Well, it turns out that birding and bird banding are just about the closest thing you can get in real life to filling out the Pokédex.
Birds have the Goldilocks number of species, which makes them incredibly appealing to pursue, study, identify, and watch. Think about it! Mammals, while are certainly *~*~*charismatic*~*~*, are mostly nocturnal. There are also like 10 of them in the world (yes, that’s an undersell). Lame! Insects and other invertebrates are amazing, but there are too goddamn many for many laypeople to really get into (side note: my alternate field would probably be malacology because I love Mollusca). Fish have some good numbers and variety, but require getting into this whole aquatic sphere– a different world entirely and one that is not readily accessible to those of us who matured in NYC.
So there’s the numbers game and their incredible charisma at play here. Humans have trained their companion psittacids and cacatuids to speak, to understand; as intelligent social animals, we can feel a mysterious connection with birds in the same way that most humans feel an inherent connection with your typical charismatic megafauna, such as wolves and lions (*eyeroll*).
3. Birds are diverse.
Cassowaries are three-toed behemoths that can communicate in rumbling infrasound like elephants and kick a grown man to death. Woodcocks can see in 360 degrees without a single turn of the head. The booted racket-tail is a hummingbird about the size of a quarter with a tail three times its body length that goes torpid every night after its daily frenzy of foraging for nectar. The Chiroxiphia manakins coordinate sexual display in an incredible show of teamwork, after which only one male gets to mate. The bowerbirds build ornate structures that rival some human creations, and then dance and sing in front of them for a mate.
Albatross can maintain a pair bond for decades, and once their chicks fledge they may not touch solid ground for three years. Steller’s eiders from both North America and Russia winter together on the sea ice of the Bering Strait, where they fish for molluscs in the cold. Bar-headed geese fly over the Himalayas. Arctic terns breed as far north as the Arctic circle and winter all the way south in Antarctica, in the longest migration known to the animal kingdom. Martial eagles kill and eat small antelope by flying them up high and dropping them to the ground. Starlings and mimids can imitate hundreds of sounds. Numerous seabirds can go their entire life without a single drink of freshwater due to their advanced salt glands.
…And so on. The breadth of the bird world is absolutely incredible. With roughly 10,000 species worldwide existing on every continent (something that cannot be boasted by many other taxonomic classes), birds have evolved to occupy so many amazing niches.
4. Birds matter.
Now, this isn’t to imply that other animals don’t matter! It is incredibly vital that we keep a steady stream of funding to all biological sciences, but I must say that in my work with birds I have always felt that the research I’ve been doing plays its part in the greater scheme of things.
Birds are an easily seen indicator species; their high sensitivity can be informative about how the world at large is doing. As climate changes and anthropogenic disturbance increases, we can see bird populations shifting their range and phenology from year to year.
Since they are so prominent, birds have also been among the numerous species to face untimely extinction; take the story of the magnificent great auk, for example, which was rapidly hunted into oblivion due to its flightlessness and colonial breeding strategy. Carolina parakeet, passenger pigeon, Bachman’s warbler, ivory-billed woodpecker, Labrador duck: these are all species that used to be seen in North America that are nowhere to be found today.
And it’s through some well-timed intervention spear-headed by biologists and conservationists that we have avoided the loss of other amazing bird species. The National Audubon Society keeps an egret in their logo, a nod to the birds that were almost destroyed in the hat trade. The Atlantic Puffin was completely extirpated from the Gulf of Maine until it was successfully reintroduced on Eastern Egg Rock. And remember the shitshow that was DDT? It was birds that let us know how much of a threat that pesticide was; brown pelicans, bald eagles, peregrine falcons, osprey, and more faced steep declines thanks to the substance.
These reasons just brush the surface of why birds are amazing– and yes, why I am constantly amazed by birds even though I look at them every day in my backyard or as part of my work. We haven’t even mentioned feathers, or vocalization, their incredible physiology, or the way they have inspired artists for centuries.
Getting into birds literally changed my life; it was a turning point for my career, for my mental health, and for my outlook on this incredible world that we live in. I want others to have similar realizations about the natural world! That’s why I run this blog, and that’s why I’ll never stop birding.
This yeti crab (Kiwa hirsuta) was discovered in 2005 and has no eyes. It was found by the Census of marine Life on a hydrothermal vent near Easter Island at a depth of 2,200 meters. Credit: A. Fifis, Ifremer/ChEss, Census of Marine Life
I desire, with all of my heart, to see a mollusc I have never seen before
The Spanish dancer (Hexabranchus sanguineus) is a large nudibranch that inhabits tropical and subtropical waters in the Indo-Pacific region. Unlike most nudibranchs, it is capable of free-swimming, using undulations of the wide, flattened edges of its mantle to propel itself through the water. The whirling motion as it swims is reminiscent of the skirt movements of a flamenco dancer, hence its common name.
Blue sea snail (Chromodoris willanii), a shell-less marine gastropod mollusk.It is most common in the seas of various islands of Indonesia. You can also find them near the shores of Philippines. Chromodoris Wilani is a sponge eater. They feed on Semitaspongia groups of sponges.
Mollusca Magica: A group of unusual species bearing striking similarity to their mundane counterparts with a variety of interesting adornments. These intelligent (although generally non-social) creatures are notable for being one of the more ‘safe’ fae species to approach and interact with. While they may not necessarily prove to be gregarious, they are only rarely noted to be malicious. Admittedly, this seems to be down to the personality of the individual in question, and different branches of the tree are known for varying levels of trickiness and communicability.
This is a soft-bodied, marine gastropod known as the Nudibranch, which includes about 2,300 different species. They live in seas worldwide and are between 4 and 600 mm. Nudibranchs are carnivorous and feed on anemones, tunicates, sponges, and sometimes other nudibranchs. They can release acidic mucous from their skin as one of their defense mechanisms.
My little pride and joy – the pleiospilos nelii plants, that I grew from seed. They actually didn’t take very long to grow. I have three such planters in my kitchen window, and they are seeming to do well there.