The Coconut Crab (Birgus latro) is the largest terrestrial arthropod on Earth, reaching up to 28 kilos with a leg span of nearly a meter! They are found on various islands and shorelines around the Indo-Pacific, where they feed on coconuts…
Want to stay on top of what’s happening with our current Okeanos Explorer expedition? Check out our daily updates: here
And be sure to tune in today (7/11/13), as we explore an area that has never been seen before, but where multibeam sonar data has detected bubbles in the water column that could indicate the presence of hydrocarbon seepage that may support chemosynthetic communities of life.
The Latin root, crustaceus, “having a crust or shell,” really doesn’t entirely narrow it down to crustaceans. They belong to the phylum Arthropoda, as do insects, arachnids, and many other groups; all arthropods have hard exoskeletons or shells, segmented bodies, and jointed limbs. Crustaceans are usually distinguishable from the other arthropods in several important ways, chiefly:
Biramous appendages. Most crustaceans have appendages or limbs that are split into two, usually segmented, branches. Both branches originate on the same proximal segment.
Larvae. Early in development, most crustaceans go through a series of larval stages, the first being the nauplius larva, in which only a few limbs are present, near the front on the body; crustaceans add their more posterior limbs as they grow and develop further. The nauplius larva is unique to Crustacea.
Eyes. The early larval stages of crustaceans have a single, simple, median eye composed of three similar, closely opposed parts. This larval eye, or “naupliar eye,” often disappears later in development, but on some crustaceans (e.g., the branchiopod Triops) it is retained even after the adult compound eyes have developed. In all copepod crustaceans, this larval eye is retained throughout their development as the only eye, although the three similar parts may separate and each become associated with their own cuticular lens. In other crustaceans that retain the larval eye into adulthood, up to seven optical units may develop.
Labrum. Crustaceans have a lobe-like structure called the labrum anterior to the mouth that partially encloses it.
Head. Crustaceans are distinguished by a five-segmented head (cephalon), followed by a long trunk typically regionalized into a thorax and abdomen.
“Baby teeth.” Most crustaceans in their early larval stages chew their food with a unique structure called a naupliar arthrite, which is on the second antenna. This chewing tool is lost later in development, and chewing is taken over by the mandibular gnathobase.
Crustacean characters can reveal evolutionary history both by their presence and absence. The naupliar arthrite is one of several characters that are helping researchers to untangle the evolutionary history of crustaceans and other arthropods (Ferrari et al. 2011). Though it is present in larvae of many Crustacea, several groups have lost it over the course of their evolution, and the ostracods never inherited it…
images: T - Sally Lightfoot Crab by Victor Burolla; 2L - Florida Crayfish (Procambarus alleni) by Jan Ševcík; 2R - by Bernard Picton; 3 - Common Pill Bug (Armadillidium vulgare) by Stanislav Krejcík; 4L - Blue Crab (Callinectes sapidus) by Jere7my; 4R - Triops by BioImages - the Virtual Fieldguide (UK); B - Palinurus delagoae by Tin Yam Chan)
We have two Puget Sound king crabs (Lopholithodes mandtii) in our crab exhibit. Bright orange when juveniles, they develop red and purple patches as they age, and are occasionally found as far south as Monterey.
Extending its arms 8 inches (20 cm) across, a pink crab perches on a bed of soft coral 2,310 feet (740 meters) deep in the Sangihe Talaud region off of Indonesia. The Little Hercules ROV captured this image of the colorful critter during a 2010 ocean expedition. Crabs like these are only found living on soft coral.
Credit: NOAA Okeanos Explorer Program, INDEX-SATAL 2010
Think all those tires, bags, shoes and bottles discarded into the ocean somehow make it back to land?
Instead of washing ashore, much of what we throw in the ocean stays there, slowly sinking to the bottom, releasing pollutants into the water, wrapping around corals, or, in some cases, becoming part of a critter-covered landscape. In the deep sea, low oxygen levels, scarce sunlight, and freezing water limit the rate at which items decompose: Something that might survive a few years on land could exist for decades underwater.
Off Southern California, an abandoned shoe rests on the ocean floor, 1,548 feet down. There’s a tire 2,850 feet beneath the surface in the Monterey Canyon. Also in the canyon? An enormous shipping container, now under 4,200 feet of water…
This stunning white crab (Caphyra sp.) is nearly invisible among the polyps of Xenia coral, found in Indonesia. It’s challenging to photograph small, well-disguised animals underwater, as photographer Marli Wakeling found while taking this photo.
See more winners of 2012’s Nature’s Best photography contest:
Discovering new species is an exciting quest, right?
Well, some parts are—but after you find a cool-looking organism that you think is a new species, there’s a lot more to be done.
Recently, a group of crab and crustacean experts locked themselves in a room together for 2 weeks to speed up the process of looking for new species among thousands of specimens collected in the Caribbean.
After several days of lost dives due to bad weather and making dives under difficult conditions, we are today in calm seas exploring an area that was discovered last year during a NOAA mapping cruise. While conducting a seafloor survey, NOAA Ship Okeanos Explorer found bubbles coming from the seafloor at a site south and offshore of Norfolk Canyon; they thought these bubbles may indicate a new methane seep site, but they had no way of verifying this idea.
Today, we deployed the Jason remotely operated vehicle (ROV) from the NOAA Ship Ron Brown to 1,600 meters (nearly a mile deep—our deepest dive yet!) to explore the area around those bubbles. After transecting over soft sediment for a short time, we saw some indications that we were getting close to a probable methane seep. These indications included white patches of bacteria on the sediment surface that feed on the methane and sulfides, plus shells of dead mussels, which are the dominant animals of methane seep communities…
She is the Red Spotted Coral Crab, but she’s not likely to tell. If you’d like to learn the names and basics about coral reef fauna- or the different penguin species of the world, or the common butterflies of North America, or any of a hundred other sets of wildlife, try the Name It app.
It’s free in the iTunes store, and will train you in recognizing and naming Caribbean reef fish, (or the trees of Switzerland, or whatever you choose), flashcard-style. The app will track your progress, and offer snippets of information about each organism.
Are you an educator training the next generation of naturalists for your region? Create your own custom deck of digital flashcards for the wildlife that interests you. All you need is a list of their names. You can create the collection on EOL and load it into the app in a few minutes.
… is native to the Bering Sea (North Pacific). It grows to a leg span of 1.8 m (5.9 ft) and is heavily targeted by fisheries.
During the 1960s this crab was introduced into the Barents Sea (North Atlantic) to provide new, valuable catch for Soviet fishermen. While populations in the species’ native range are experiencing a steady decline, the crabs are quickly expanding in the North Atlantic raising concerns about their impacts on native communities.
also known as the globose sand crab, the purple globe crab is a species of purse crab native to the waters off of Northern Baja California. Globe crabs spend most of their days partially tucked into the seabed to hide from potential predators. Like most crabs the purple globe crab is a predator and will feed on small invertebrates and organic materials.
Noises from humans like road and ship traffic, coastal development, sonar, pile driving, rowdy and drunk spring breakers have greatly altered the oceanic soundscape. These foreign noises can stress an animal as it prepares for action like fighting, hiding, or fleeing. After playing recorded ship sounds, the oxygen consumption of shore crabs (Carcinus maenus) were greater than those experience just ambient noise. In other words the ship noise made the crabs a little more crabby.
In some cases respiration was two times greater and on average was 67% higher. And fatter, ahem larger crabs, demonstrated a greater response than smaller crabs. Because larger crabs and animals in general respire more, larger crabs can also consume proportionally greater oxygen when stressed. Crabs repeatedly exposed to ship noise over two weeks eventually demonstrated less and less of stress response. One is that they simply no energy left to respond (I can only get excited once scenario) or simply acclimated to the sound when no threat presented itself (The boy who cried wolf scenario)…;
Wale MA, Simpson SD, Radford AN. 2013. Size-dependent physiological responses of shore crabs to single and repeated playback of ship noise.Biol Letters. 9: 20121194. http://dx.doi.org/10.1098/rsbl.2012.1194