Researchers have found that hagfish—a sea creature that looks like an eel but isn’t—absorb nutrients through their skin and gills.

Hagfish are pretty gross to start with.  They scavenge the sea floor looking for dead bodies. When they find one, they enter the body and eat their way out. And, according to Science Now,

…not with any sort of politesse, either. When they can’t pack enough flesh into their tentacle-lined mouths, hagfish absorb the carcass’s nutrients right through their skin.

Num!

This isn’t unusual in the marine world, says Science News, but it is for this type of creature:

Plenty of marine animals without backbones can feed through their skin, but no one had demonstrated the power in a species so close to fish and modern vertebrates…

(There is argument whether hagfish are true vertebrates because they possess the skull but not the spine required, but that’s another discussion.)

The researchers, published this week in the Proceedings of the Royal Society B, tested this using live Pacific hagfish skin and gill tissues. Again, from Science News:

Then researchers exposed the outside of the tissues to varying solutions of two amino acids and checked the other side of the tissue to see how much of the nutrients passed through, and under what circumstances.

The tissues took in the substance, and as Ed Yong writes on Discover, the researchers

…found that a hagfish’s skin can absorb nutrients faster than its intestines!

Testing on real, entire, live hagfish is proving to be challenging, but it is very likely that these resourceful creatures are encountering high levels of dissolved organic nutrients inside their corpse dinners.

Gross, but clever!

Image by wundoroo/Flickr

Much of the news is alarming. Using data on more than 25,000 species, the current results show that, on average, 50 species of mammals, birds and amphibians move closer to extinction each year due to the impacts of agricultural expansion, logging, over-exploitation, and invasive alien species.

Birds are faring the best, amphibians, the worst. The paper highlights that the percentage of species threatened among vertebrates ranges from 13% of birds to 41% of amphibians. Although the study focused on vertebrates, it also reports on the levels of threat among several other groups assessed for the IUCN Red List, including 14% of seagrasses, 32% of freshwater crayfish, and 33% of reef-building corals.

The study involved some 174 authors from 115 institutions and 38 countries. It was made possible by the voluntary contributions of more than 3,000 scientists under the auspices of IUCN’s Species Survival Commission. One of the authors is the Academy’s own mammalogist Galen Rathbun, who contributed data to the report on the status of the members of the Afrotheria supercohort, an ancient group of African mammals that includes elephants, sea cows, hyraxes, sengis (also known as elephant-shrews), tenrecs, golden moles and aardvarks. Of the 83 species currently recognized in this supercohort, 30 are considered Threatened, and an additional eight species are considered data deficient—these species are quite possibly threatened, but scientists don’t know enough about their distribution to be able to assign them a status.

Now for the good news in the report—conservation programs are working. This is the first study to present clear evidence of the positive impact of conservation efforts around the globe. Results show that the status of biodiversity would have declined by almost 20% if conservation action had not been taken.

The study highlights 64 mammal, bird and amphibian species that have improved in status due to successful conservation action, including three species that were extinct in the wild and have since been re-introduced back to nature– California Condor, the Black-footed Ferret and Przewalski’s Horse. (Last spring, Science in Action produced a video on the Condors’ recent success at Pinnacles National Park.)

Can we learn from this and expand these conservation efforts? An article in Nature concludes this way:

Although the Nagoya negotiations are currently stalling on detailed aspects of conservation funding and access to the resources of ecologically rich nations, [lead author of the study, Michael] Hoffmann remains optimistic. As he concludes from his review of conservation efforts: “We can really turn things around and that’s a powerful message — you should never give up hope.”

Wikipedia image by Bob the Wikipedian, using images from Christian Jansky, J. Patrick Fischer, BS Thurner Hof, Trisha Shears and NOAA

The findings are astounding and the images amazing! (Check out New Scientist and National Geographic for images and video of some of the stranger creatures catalogued.)

According to Scientific American:

The latest findings profile the diversity and distribution of known species in 25 important marine areas, including temperate, tropical and polar oceanic waters such as the Caribbean, Baltic and Mediterranean Seas as well as the Gulf of Mexico. The data provide a baseline for marine diversity that will be useful when assessing the future impacts of humans and nature on pelagic life.

The results from the marine areas show over 230,000 species, although scientists believe that there are more than a million more to be discovered. Japanese and Australian waters appear to be the most diverse, with about 33,000 species each.

The breakdown of life may surprise you. Science News reports that:

Big stuff… such as species of whales or turtles or sea lions, barely amounts to a drop in the oceanic bucket. Census data indicate that crustaceans are the largest chunk of known marine creatures, including crabs, shrimp and the unsung but ecologically crucial krill.

The full breakdown follows:

• 19% Crustaceans (including crabs, lobsters, crayfish, shrimp, krill and barnacles),
• 17% Mollusca (including squid, octopus, clams, snails and slugs)
• 12% Pisces (fish, including sharks)
• 10% Protozoa (unicellular micro-organisms)
• 10% algae and other plant-like organisms
• 7% Annelida (segmented worms)
• 5% Cnidaria (including sea anemones, corals and jellyfish)
• 3% Platyhelminthes (including flatworms)
• 3% Echinodermata (including starfish, brittle stars, sea urchins, sand dollars and sea cucumbers)
• 3% Porifera (including sponges)
• 2% Bryozoa (mat or ‘moss animals’)
• 1% Tunicata (including sea squirts)

The remaining categories are other invertebrates (5%) and other vertebrates (2%). The scarce 2% of species in the “other vertebrates” category includes whales, sea lions, seals, sea birds, turtles and walruses. Thus some of the best-known marine animals comprise a tiny part of marine biodiversity.

These results are incredibly important so scientists can protect the life that is out there from various threats. Again, from Scientific American:

The researchers emphasize overfishing as the top threat to marine life worldwide. It impacts diversity and alters food webs in the sea by depleting the targeted, exploited species as well as reducing other animals commonly found in by-catch. Other threats of chief concern highlighted in the report are habitat destruction, pollution, invasive species and warmer waters due to climate change.

Image by Tin-Yam Chan, CoMarge

In 1888, scientists discovered that a type of algae grows inside the eggs of spotted salamanders as the embryos develop. Biologist Renn Tumilson describes the process this way on the Henderson State University website:

The alga, called Oophila amblystomatis (which means “loves salamander eggs”) can invade the membranes of the eggs and grow there.  The alga photosynthesizes and produces oxygen near the embryo where it is needed.  In exchange, the carbon dioxide released by metabolism from the embryo is just what is needed by the alga.

Scientists studying the symbiotic relationship believed the algae only existed inside the eggs. But last week, scientists speaking at the Ninth International Congress of Vertebrate Morphology in Punta del Este, Uruguay presented new findings that show that the algae are actually inside cells covering the salamanders’ bodies. As reported online by Nature, the symbiosis continues:

Moreover, there are signs that intracellular algae may be directly providing the products of photosynthesis — oxygen and carbohydrate — to the salamander cells that encapsulate them.

One of the researchers, Ryan Kerney of Dalhousie University, was staring at the eggs when he noticed the algae green “comes from within the embryos themselves, as well as from the jelly capsule that encases them.”

Where that algae come from still baffles the researchers. One possibility is that the algae are passed down from the mother. Nature gives another possibility, too:

Because salamanders can re-grow limbs, almost all the cells in a grown adult retain a degree of pluripotency — that is, the specialized cells can continue to divide and change into other cell types throughout the salamander’s life.

It may be that specialized cells in these adult salamanders are able to accommodate algae inside them because the process by which they learn self-recognition is different from that of other vertebrates.

Algae have been found in similar symbiotic relationships with invertebrates like corals, but this is currently the only example with vertebrates. Scientists wonder if there could be more salamanders that hold algae so dear. According to Nature, Congress attendee Daniel Buchholz, a developmental biologist at the University of Cincinnati in Ohio, said, “I think that if people start looking we may see many more examples.”

Creative Commons image by Scott Camazine