Slipper snails live in the intertidal where they attach to a rock or often the shell of another snail. Are these snails male or female, or first one then the other? The answer is yes to all those questions. Slipper snails start life as males and change to female. This strategy is called sequential hermaphroditism. These snails change sex when they reach a certain size, depending on the sexes of the other slipper snails around.
Just like us, larvaceans are chordates. These small tadpole-like animals live at midwater depths of the world’s oceans. All species construct complicated, mucus structures, called ‘houses’ where the animal lives. To feed, the larvacean beats its tail, pumping seawater through its house. The sticky filter structure has two parts: the outer filter traps coarse particles; the inner traps fine ones. When the house becomes clogged, the animal discards it and it sinks to the bottom. In Monterey Bay, there are giant larvaceans that create large houses that can exceed one meter (three feet!) in its greatest dimension.
Like monarch butterflies, dragonfly migrations are multi-generational journeys. The dragonflies migrate to maximize breeding opportunities in warm water ponds. They build up fat reserves before setting off, just like migratory songbirds do. And some species even follow the same migratory pathways as songbirds. Dragonflies can fly up to 100 miles a day (160 km). People have observed dragonfly migrations on every continent except Antarctica.
Green darners, fly each summer to the northern U.S. and Canada to breed. Their offspring return south in the fall. If you’re lucky, you might see these and other species as they fly south by the millions. About 16 of 326 North American species migrate. The major migratory species in North America are: common green darner (Anax junius, wandering glider (Pantala flavescens), spot-winged glider (Pantala hymenaea), black saddlebags (Tramea lacerata), and variegated meadowhawk (Sympetrum corruptum).
Even though sea cucumbers don’t look much like sea stars and sea urchins, they are all echinoderms. If you look on the underside of a sea cucumber, you will see it is covered with tube feet. Some have surprising defenses to predators – we might call them gross. When attacked, the cucumber spews out sticky threads from its anus, tangling the hunter. Others can expel their entire guts out their anus. This may confuse, repel or feed predators. As extreme as this defense sounds, a cucumber can quickly regenerate its inner organs.
The Kind of Luck Your Health Depends On!
Horseshoe crabs come from an ancient line. Their ancestors appeared in the fossil record about 500 million years ago. And, while the horseshoe is a very auspicious symbol that is used to protect against any forms of evil, the horseshoe crab protects many of us from many diseases.
Over the millennia, this group has developed a trait unique to the horseshoe crabs alive today: their copper-based blue blood contains bacteria fighting compounds that cause the blood to clot when exposed to bacteria fragments.
Who knew scaly skin could be so silky?
Although velvet worms are called worms, they are neither the familiar Annelid nor Flatworm. In fact, they are a phylum of their own (and, no-- Shape of Life doesn’t include that phylum). Their name – Onychophora – means “claw-bearer”. Thought to be a missing link between Arthropods and Annelids, scientists now think that these ancient worms are more closely related to Arthropods.
A Swell Goiter!
Goiter sponges, like the one here, live in cold, deep waters – 300-4,000 feet—often on seamounts. These sponges average about three feet across but can grow to be nearly 10 feet across. Like most sponges they are filter feeders, pumping in seawater and extracting food particles from the water.
In the Pacific Northwest, goiter sponges and other glass sponges build deep-sea sponge reefs. The sponges’ dense, silica (glass) skeletons remain after a sponge’s death, forming an ideal surface for yet more sponges to grow on. The three-dimensional structure of these reefs is comparable to coral reefs and provides habitat for a diversity of creatures.
Giant Clams are in a Giant Jam!
Why Protecting Giant Clams is GIANT!
Giant clams are the largest bivalves on earth, as well as the largest in the fossil record. They are indeed giants: they can grow to four feet wide and weigh as much as 500 pounds. It’s the clam’s colorful mantle, often an iridescent blue, that’s easy to spot. The clams create that blue color to direct sunlight to the tiny algae – called zooxanthellae – that live within. Just as with corals, the algae produce nutrients for the clams. They also feed on plankton drifting by. Giant clams live on shallow coral reefs in the South Pacific and Indian oceans.
Unfortunately for the all the giant clam species, their meat is considered a delicacy in many places in Asia, and so some populations have disappeared while others are officially listed as Endangered or Vulnerable. Local island people who depend on the clams for food can’t find any. In a sad twist in today’s conservation challenges, the anti-poaching effects on the supply of elephant ivory has led to Chinese boats destroying coral reefs to harvest giant clams. There is a new market for their shells to replace elephant ivory for carving.
Many species of flatworms live in marine environments. They are simultaneous hermaphrodites, meaning they are both male and female. It's advantageous to be a hermaphrodite since the odds of successful reproduction are doubled. What’s the strategy for reproducing if you’re both male and female? It’s complicated. When a pair of flatworms of the same species meets, each can deliver sperm or receive it for fertilizing eggs internally. There’s a natural conflict since it takes a lot of energy to grow and carry fertilized eggs, so each animal wants to be the male.
Keep Your Friends Close, BUT! … Your Anemones CLOSER!
Sure, there were lots of reasons for Nemo to bust out of that Dentist office aquarium. In our version of the story, it was mostly because he couldn’t bear to live outside of his anemone.
Nemo is a clownfish, also known as anemonefish because these fish make their homes in anemones. Of over 1,000 anemone species worldwide, only 10 coexists with tropical clownfish. The fish and its anemone are in a symbiotic relationship – this means that the fish benefits from the anemone and vice versa.
Clownfish are the only fish capable of living in an anemone without getting stung by its tentacles. Like their relatives, jellies and corals, anemones have stinging cells on their tentacles. How do the clownfish escape being stung? They have a slimy mucus covering that protects them from the stinging tentacles. Scientists know this because they took clownfish, wiped off the covering, and found that the fish would get stung when they were returned to their home anemone.