“Pyrosomes, genus Pyrosoma, are free-floating colonial tunicates that live usually in the upper layers of the open ocean in warm seas, although some may be found at greater depths. Pyrosomes are cylindrical- or conical-shaped colonies made up of hundreds to thousands of individuals, known as zooids. Colonies range in size from less than one centimeter to several metres in length.
Each zooid is only a few millimetres in size, but is embedded in a common gelatinous tunic that joins all of the individuals. Each zooid opens both to the inside and outside of the “tube”, drawing in ocean water from the outside to its internal filtering mesh called the branchial basket, extracting the microscopic plant cells on which it feeds, and then expelling the filtered water to the inside of the cylinder of the colony. The colony is bumpy on the outside, each bump representing a single zooid, but nearly smooth, though perforated with holes for each zooid, on the inside.
Pyrosomes are planktonic, which means their movements are largely controlled by currents, tides, and waves in the oceans. On a smaller scale, however, each colony can move itself slowly by the process of jet propulsion, created by the coordinated beating of cilia in the branchial baskets of all the zooids, which also create feeding currents.
Pyrosomes are brightly bioluminescent, flashing a pale blue-green light that can be seen for many tens of metres. The name Pyrosoma comes from the Greek (pyro = “fire”, soma = “body”). Pyrosomes are closely related to salps, and are sometimes called “fire salps”.
Sailors on the ocean are occasionally treated to calm seas containing many pyrosomes, all luminescing on a dark night.” (x)
The striped pyjama squid is one of the few known poisonous cephalopods (squid, octopus, cuttlefish, and nautilus) that roam the seafloor of the Indo-Pacific Oceans, along with the flamboyant cuttlefish and the southern blue-ringed octopus.
So today at the zoo Carlito our giant anteater bent the edge of his water pool tub so that it would start flooding his exhibit and then gave himself a bath
I received this question today, I have to say this puzzled me the whole day. Let’s delve into the subject I never thought I would delve in: cephalopod jaw evolution!
Behold, the beak of a very large species of squid. Some people use it as the perfect example of convergent evolution: both birds as well as cephalopods developed a sturdy beak to crack hard materials (e.g. nuts, shells or crabs). But to be quite honest, the evolution and possible precursor of the cephalopod jaws have puzzled scientists for ages.
Beak of a freshly caught squid. Royal society of Chemistry; Photographer: Mark Conlin
Let’s first address the elephant in the room, the squid jaws are not homologous with the radula we know from snails. Even more interesting, squid, octopi and cuttlefish even have a tongue-like radula behind the two jaws to scrape the flesh of their prey. But if the jaws are not a derived form of the radula, what are they derived from?
Let’s say you’re a cephalopod in the late Jurassic period, the sea is full of predators and you need to protect yourself. You have your hard shell, but the predators can just get in there through the front door. Thank your ancestors, because you have what you call an operculum, a hard plate you can use to close your shell. Dzik describes the evolution of the cephalopod operculum in detail as part of his thesis in 1981. Here he explains, based on fossils and previous findings by other authors, that the operculum in the “Hypothetical ancestor of all shelled mollusks (Coniconchia)” can also be found in the most basal groups of cephalopods (Endoceratida):
Evolutionary relationships between main groups of early Cephalopods, with medial sections and apertural views of all groups. Dzik, 1981
In more derived groups, something interesting happened: the operculum splits in two parts, in structures we call the Aptychi. During evolution, the aptychi migrated deeper inside the body, but could still be pushed to the outside to act as an operculum. While the aptychi are retracted, the pointy ends emerged a little and could be used as some way to destroy sturdy preys, like shelled invertebrates, thus functioning like mandibles or real “jaws”.
Some examples of aptychi (top right: Oppelia from Late Jurassic of Solnhofen, Germany; bottom left: aptychi (recto and versus) from Late Jurassic of Lombardy, Italy), and conceptual scheme of their function if indeed they were used to close the shell aperture, as opposed to being jaws. Wikipedia commons; Antonov
Aptychi are often found inside the shell of ammonoids, together with a single plate, what we call an Anaptychus. The function of the Anaptychus, closing the upper part of the shell-opening, can still be found in extant nautili (Nautilus sp.), where a leathery flap closes the shell. It is believed that modern day cephalopods simply removed the problem of protecting the shell entrance by having new structures take care of that (like in the case of the nautilus), or by just loosing the shell partially (e.g. cuttlefish, squid) or even entirely (octopi).
The diet of extinct cephalopods cannot easily be studied, so we cannot be totally sure on where the closing-hatches were used for. For now, this sounds like the most plausible explanation, but there’s still a lot to be discovered.
Octavio was playing with this clear barrel he was given for enrichment. It had food in it hours before this video was taken, which he ate. So that means he is just chilling in it because he wants to. He would also slightly lift it up every once in a while.
Scientists studying methane seeps deep in the Atlantic Ocean happened across this skull of a baleen whale. The whale species wasn’t identified, but baleen whales include: right, pygmy right, gray, and rorqual, a group that includes humpbacks and the largest known animal on Earth – blue whales.
