These lobsters are usually happy to stay inside their special
enclosure. However, we recently had one feisty lobster get out of his enclosure
at night and found a nice spot to live inside the rockwork. While he wasn’t
doing any harm inside the rockwork, the staff wanted to find him a new home and
needed a way to get him out. So how do you catch a little lobster? With a
little lobster trap, of course!
Finished trap
Michael O’Neill, a Visitor Educator in the Visitor
Experience Department (who's also volunteered with the Rescue Dept.), also happens to be a volunteer for the Edge of the Sea
exhibit. Hearing of the lobster’s escape, he decided to put his building skills
to good use. Using small pieces of wood, dowels, mesh from an old dive bags,
cable ties and some metal rings, Mike created a fairly accurate 1/8th
scale of a lobster trap.
Construction started...
Nets being added
After spending a couple of weeks on construction, the trap
was ready to be deployed in the exhibit. Mike cleared out a space in the tide
pool, placed the trap on the bottom and then baited it with small pieces of smelt.
The wait began…
Deploying the trap in Edge of the Sea
A month had gone by…nothing. The trap remained empty.
However, late last week, success! Upon opening the exhibit in the morning,
educators found the lobster in the trap-the trap had worked! During the evening
hours, the lobster had made his way out of his hiding place, took the bait and
landed in the trap!
Caught ya!
Visitors and staff, especially Mike, were happy to see that
the trap worked! Innovation, some wooden dowels and a fun idea managed to catch
our lobster Houdini and show to visitors how lobster traps work! Let’s hope
that the little lobster stays put for now!
Happy Mike!
Update! Researchers have found that lobsters spend
relatively little time in lobster traps, able to climb out after getting a
snack. True to form, our little lobster remained inside the trap for one day…and
managed to escape back into the exhibit rockwork later that night. Looks like
the trap has some more work to do!
The green sea urchin (Strongylocentrotus droebachiensis) comes from the class of animals called Echinoidea, which means "like a hedgehog." Can you guess why?
Green sea urchin at the New England Aquarium
Young hedgehog (Photo: By Calle Eklund/V-wolf, via Wikimedia Commons)
Sea urchins are related to sea stars, sand dollars and sea cucumbers. You can find urchin species in oceans around the world (and in the Edge of the Sea Touch Tank here at the Aquarium!). The green sea urchin prefers shallow, rocky areas. They snack on algae and dead matter by scraping with five pointed teeth.
Urchins can destroy kelp beds and are sometimes seen as pests! An urchin's mouth structure is also called an Aristotle's Lantern. It
contains the five teeth and also has 40 different skeletal parts and 60
muscles.
Urchins can move at a rate of six to seven feet per hour. They use their spines and tube feet, also called podia, to get around. Each spine is attached with ball and socket joint.
Look closely and you can see the podia in this picture.
Podia are long and slender with terminal suckers at the end. Tube feet operate hydraulically by means of a water vascular system.
Urchins often cover themselves with pebbles, shells, and bits of seaweed for camouflage.
Sea urchins have a long list of predators, and people are tops on that list. Marine birds, arctic foxes, sea otters and starfish also eat urchins. Wolffish swallow urchins whole. Triggerfish blow them over with a jet of water. Gulls pick the urchins from a tide pool, fly overhead, and drop the animals onto the rocks. The shell breaks open on impact and the gull flies down for its meal.
Group of green sea urchins in the Aquarium's Edge of the Sea exhibit
Conservation Notes: Sea urchin roe (actually both the male and female gonads), called uni in Japan, is considered a delicacy. During the "Green Gold Rush" of the 1980's and 1990's, millions of pounds of urchins were harvested for their roe. Overharvesting amid a lack of regulation caused the urchin population to crash. Regulations now prevent overharvesting of urchins, but populations have been slow to recover.
Aquarist Dave Wedge recently grabbed some special video of a female Acadian hermit crab (Pagurus acadianus) hatching her eggs. You can see her remove her tail from her shell to fan the eggs so the larvae can disperse into the water column. Those larvae are tough to see, but look carefully and you can spot them sparkling at the surface of the water during the close-up!
Female hermit crabs carry their eggs for a couple weeks before releasing the larvae into the water. You might be able to spot this kind of behavior at the Aquarium's Edge of Sea exhibit the next time you visit! Just ask anyone with the Aquarium logo on their shirt to point out a hermit crab in this hands-on touch tank.
A guest post from Lisbeth Bornhofft Lisbeth is a Senior Aquarium Educator who has also contributed to the Rescue Blog. You may have seen her around the building answering visitors' questions or offering up an interesting bit of information about a particular animal or exhibit. Here she shares her knowledge with readers of the Exhibits Blog!
If you spend some time at the Edge of the Sea exhibit, you can learn some fascinating facts about the most popular echinoderm and one of the ocean's most recognizable inhabitants: the sea star.
For example, an Aquarium educator might teach you how sea stars circulate salt water throughout their body and use it to propel their tube feet, which helps them get around. They also have clusters of nerves called eyespots that help them detect light and dark.
Tip of sea star arm with eyespot and sensory tube feet
Some sea stars eat mollusks, like clams and mussels. Others dine on a variety of foods like microalgae, other sea stars or even small fish! (Learn about other cool sea star eating habits here and here.) Their mouths are located on their bellies. Many species are able to start digesting their food before it goes into their bodies by everting their stomachs!
Northern sea star with stomach everted, photo: Lisbeth Bornhofft
During a busy week recently, our visitors asked some interesting questions that I thought I'd share with you.
I used to see so many sea stars when I was little and now I can never find them.
It seems there are fewer sea stars than there were 50 years ago, but the truth is that sea star populations have not been studied enough for us to know how their numbers have changed and what has impacted them. Sea stars are subject to all the usual threats, such as chemical pollution, coastal development and warming oceans, plus over-collection as ornamental keepsakes. Since water is pumped directly into their bodies via the water vascular system, sea stars have little or no ability to filter pollutants and toxins out of the water. This makes them highly susceptible to damage from pollution and contaminants.
I have a sea star on my Christmas tree. It was already dead when I brought it home from the beach.
Most the sea stars that you see in the wild are probably alive. Dead sea stars disintegrate quickly unless left high and dry. Even an active sea star will pull in its tube feet when disturbed and may appear to be dead.
Do sea stars have a skeleton?
Sea stars are invertebrates, but they do have a supportive structure (endoskeleton) composed of calcium carbonate components, known as ossicles.
That sea star has fungus on it.
Sea stars breathe through their skin, which is covered with small, finger-like papula for the exchange of gases. When these "skin gills" are extended, the sea star might look fuzzy, but it's not fungus.
Check out these close-up clips showing the surface of a sea star!
Can sea stars pinch?
Well, that all depends on how big you are! They can certainly pinch small creatures that crawl on top of them. Sea stars have small pincer-like structures called pedicellariae that cover the upper (aboral) surface. They use these pincers for protection, but also to help remove debris (detritus) that has fallen from above.
A magnified image of a tiny caprella skeleton shrimp on Forbes sea star, photo: Lisbeth Bornhofft
Are sea stars poisonous?
None of the sea stars at the Aquarium are dangerous to humans, however many species of sea stars in the wild do contain toxins. People of some cultures have been known to eat sea stars, especially the gonads, but there are also reports that dogs and cats have become violently ill or died after consuming sea stars. Of the approximately 2,000 types of sea stars, the crown-of-thorns may be the only sea star that is venomous. Filled with toxin, the spines can break off and penetrate the skin causing a sharp burning pain, swelling and numbness.
Crown-of-thorns sea star photographed by Aquarium researcher Randi Rotjan. Read about her research expedition to the Red Sea on the Global Explorers Blog.
Why do they curl their arms up?
At our exhibit, this behavior is commonly thought to be a sign of stress. When we see that, we usually give the animal a little time-out so it can rest. In the wild, however, a sea star can move to a different mussel or oyster bed by curling its arms to release its hold and drift with the tide.
How do sea stars hold on?
Contrary to popular belief, the gripping action is a function of adhesive chemicals rather than suction. A second adhesive secretion breaks the bonds and allows the tube feet to be released. Tube feet consist of internal bulbs called ampullae and external podia, (feet). The ampulla forces water into the foot, which expands to contact the rock or other substrate.
The undersides of a Northern sea star, photo: Lisbeth Bornhofft
How can they live without a brain?
Lots of species don't have brains and have been successful on our planet (like jellies, for example)! Echinoderms like the sea star have somewhat complex nervous systems, but don't have a true centralized brain.
Do sea stars have eggs?
Yes, and sperm, too. Sea stars usually reproduce by broadcast-spawning: They release their gametes into the water where they are fertilized by gametes from the opposite sex. Sea stars probably use environmental signals as a cue to gather in groups when they are ready to spawn. Some species can also reproduce asexually by regeneration. A detached arm can sometimes develop into another sea star.
Look at the baby sea star!
A "baby" sea star is so small that you would need a microscope to see it. Besides, you would probably not even recognize it as a sea star—the larval form is a completely different shape and is free-swimming.
Are there freshwater sea stars?
Sea stars do not to have mechanisms for osmoregulation, that is, they are not able to adjust the concentration of salt in their bodies. They keep their body fluids at the same concentration as the surrounding water. Although some species can tolerate brackish water, the lack of osmoregulation explains why sea stars are not found in fresh water.
Do you have other sea stars at the Aquarium?
There are sea stars (Asteroidea) or brittle stars (Ophiuroidea) in almost every gallery of the Aquarium! Ask someone with an Aquarium name tag to point them out to you.
