Sheepshead (Archosargus probatocephalus)
The sheepshead is a marine fish that grows to 30 in, but commonly reaches 10 to 20 in. It is deep and compressed in body shape, with 5 to 6 dark bars on the side of the body over a gray background. (wiki)
The cool thing about these buggers is the teeth. They have nicer, straighter teeth than I do. Also, they apparently taste pretty good.
(via mogget)
Tongue-eating louse (Cymothoa exigua)
The tongue-eating louse, is a parasitic crustacean of the family Cymothoidae. This parasite enters fish through the gills, and then attaches itself at the base of the fish’s tongue. The female attaches to the tongue and the male attaches on the gill arches beneath and behind the female. Once in the mouth, it extracts blood through the claws on its front, causing the tongue to atrophy from lack of blood. The parasite then replaces the fish’s tongue by attaching its own body to the muscles of the tongue stub. The fish is able to use the parasite just like a normal tongue. It appears that the parasite does not cause any other damage to the host fish.Once C. exigua replaces the tongue, some feed on the host’s blood and many others feed on fish mucus. This is the only known case of a parasite functionally replacing a host organ.
Image source
(via al-khowarizimi)
1. HIV has surface proteins called gp120 that attach to cells with CD4 receptors on their surfaces. CD4 is found on helper T-Cells, and on macrophages of the immune system.
2. The HIV virus binds with the cell, and the soon to be host cell incorporates the virus’s membrane into its own and the viral core enters the host cell. Upon entrance, the virus loses its membrane—allowing it to introduce its RNA into the cytoplasm.
3. Viral enzymes convert the viral RNA into DNA, and the viral enzyme reverse transcriptase copies the RNA into complementary DNA (cDNA). Reverse transcriptase has a high error rate, and frequently mutates the copied DNA—allowing the virus to evolve quickly.
4. The viral RNA is destroyed by another viral enzyme called ribonuclease H, and then reverse transcriptase synthesizes a second DNA strand using the first as a template.
5. The double stranded viral DNA enters the nucleus with the help of viral proteins, and integrase enzymes splice the viral DNA into the cell’s chromosomal DNA. This strand is known as provirus.
6. The synthesis of the viral genome begins with the transcription of this proviral DNA into RNA, which contains the code to produce capsid proteins (and others) needed for viral assembly.
7. In this spliced form, the RNA codes also for the envelope proteins and other auxiliary proteins. These are produced in the rough ER, then moved through the golgi before arriving at the cell surface.
8. Full length viral RNA molecules, along with all other viral components, assemble at the membrane and bud off the cell. It’s not clear how HIV stops the immune response, nor how it causes the destruction of T cells—it ultimately results in the loss of all functional T helper cells in the immune system.
Antibodies - Your body’s Kamikaze
Opsonization is the process of ingestion and destruction of a pathogen by a phagocite. It starts with the antibodies recognizing the antigen on the bacteria and attaching to the epitope of the antigen. Once the anitbody attaches to the antigen’s epitope, the Fc region of the antibody changes structure. The changing of the structure of the Fc region signals the Fc receptor on the phagocite to attach to the Fc region, and engulf the bacteria—along with the antibody—and destroy it all.
The process of opsonization for viruses is slightly different, as the virus infects cells instead of being an actual body as is the bacterium. The host cell indicates that it is infected by the virus by putting out flag antigens, which signal to antibodies to attach to the antigen’s epitope. When the antibody attaches to the epitope, the structure of the Fc region changes, signaling to the Fc receptor that it needs to destroy the host cell, virus, and antibodies.
Cookiecutter shark (Isistius brasiliensis)
This tiny little beauty (17”-22” in length) can gauge a round plug out of its pray. It swallows smaller prey whole, but it stealthily attacks larger prey and sometimes submarines and underwater cables. It’s not likely that you’ll come across this pretty species of dogfish shark, but if you do, it’ll attach to you with suction lips and take a nice round chunk out of you.
Jellyfish, by Alexander Semenov
Open-heart surgery requires an armamentarium. With a skin knife, the surgeon makes an incision, then uses a Weitlaner retractor to spread underlying tissues. After the sternum saw has cut through the breastbone, the Finochietto retractor pushes aside tissue and bone to bare the heart. Sutures, largest to smallest, close the sternum, pericardium and incisions on the heart. The rake retractor and needle holder hold skin and tissue in position during suturing.
(via articulomortis)
Cilia in bronchiole of lung
The cilia in the lungs and respiratory tract serve to push mucus towards the trachea so that it is able to proceed down the esophagus.
Cleaning Symbiosis
If you’ve seen Finding Nemo, you probably remember the little french shrimp, Jacques. Jacques, a Pacific cleaner shrimp (Lysmata amboinensis), always made sure the tank was clean, and was appalled when everything was filthy. But, this behaviour is not limited to cartoon films—there are little Crustaceans all over the watery world, who like Jacques, enjoy “cleaning” their environment—and sometimes their fishy counterparts.
It has been observed that different species of fish will “line up” in a set up that’s similar to one would see at a car wash. The fish wait for their turn to be cleaned by little crustaceans and even some cleaner fish, like wrasses (Labroides dimidatus) and gobies (Genus Elacatinus). These cleaner fish/shrimp will remove and eat any parasites off the skin, both internally and externally.
There are many incredible parts to this cleaning symbiosis. Some of the fish that come to be cleaned would actually, under other circumstances, eat the cleaner fish or shrimp. Perhaps the most incredible thing about these cleaning stations is the fact that there are many different species of both cleaned fish and cleaner fish/shrimp in these cleaning lines, but they somehow manage to communicate and get through the cleaning. This communication between species is evidence that some chemical exchange must be occurring.
