By: Dr Nerida Wilson, Category: Science, Date: 03 May 2013
We had a fifth grade science class at Heritage Elementary, Escondido, California send us questions about our work.
3 May: Answers for class (Scotia Arc Expedition 2013) #2
Photographer: Greg Rouse © Australian Museum
Here we’ve posted some answers for them...
Q: What will happen if you find the Porania sea star? Why are you looking for it?
A: Thankfully we did find the Porania sea star in a lot of places we looked at, but not everywhere. We are trying to understand how far animals can move in these oceans. There is a very strong current between Cape Horn at the bottom of South America, and the Antarctic Peninsula, so small animals and larvae from these animals could not swim across, but they might hop from one “underwater island” to another. Whenever we find Porania, we give it a number and photograph it, and we then fix it in chemicals that will preserve the animal so that we can take it back to the museum and sequence it’s DNA.
Q: How do you know when the trawling net touches the bottom of the ocean?
A: The crew of the ship has done this many times and they are very experienced, so most of the time we ask them! They measure the tension of the wire that the net is attached to. The net opening is fixed to a big and very heavy iron frame that keeps the net open and on the bottom. All of this (the depth, the wire tension, time etc.) is monitored by a computer that we can all look at on board of the ship. When the tension goes up and the wire is the right length for that depth, we know we have hit the bottom.
Q: What kind of species most often appear in the nets you bring up after a trawl is completed?
A: This really depends where we are. Sometimes the species that we see most often are sponges and sea cucumbers. And sometimes it’s brittle stars. Or feather stars. The bottom of the sea is not all the same. Compare it to land, where there might be fields, or forests or mountains, with different animals living in those different environments.
Q: Is being out at sea scary or fun?
A: It can be both. Generally it is fun, but we went through a pretty bad storm on April 22. Storms and big waves can be a bit scary. Thankfully the ship is very stable and big and the captain and first and second mates that drive the ship are all very good at keeping the ship safe and comfortable. We went through the winds and waves without any problems. Most of the time it is a lot of fun and always interesting. One thing we do in our free time is playing a Ping Pong tournament, which is a lot of fun.
Q: Is the research you are doing on the ship beneficial? How so?
A: We all believe it is. When people estimate how much there is explored about ‘life in the ocean’ it is not much more than 2%. That is for all marine waters, tropical, temperate and arctic. Of course Antarctica is a lot harder to get to, and you can’t just hop in and dive down, especially in deep waters. Our work here helps to understand the connectivity of animals in the ocean. We want to understand how far animals move around here.
Q: Why has each of you chosen these career paths?
A: We are all very curious people and like to understand how thing work. Our interests are different, some like to observe animals to understand their behaviour, some like to do chemistry to for example to understand how an animal can protect itself with a poison, and others like to understand how things are connected, for example why an animal on the southern hemisphere can have a close relative on the northern hemisphere. Once we realised we like science we specialised in a field that we liked and are good at.
Q: About how many people are on the ship?
A: There are 9 people on the science team and 20 crew.
Q: What is the rarest thing you have found so far?
A: That really depends on what you mean. There are many animals we have seen here that have not been seen much before- but that might be because no one has looked for them. So animals can be common in their habitat but hard to actually see (especially if they live in places that are hard to look in, like the deep sea). Also, some animals are common in some places, and rare in others. For example, it would be rare to see an albatross in Australia, but we see many down here.
Q: How do you make nitrogen ice cream?
A: Have you learned about liquid nitrogen (N2) yet? It’s a gas that can get sooooo cold (minus 120 deg C) that it becomes liquid and you can use it to freeze things really quickly and really cold. In science we often use it to preserve samples. When you pour it over something that is not as cold, the liquid nitrogen warms up and becomes a gas again. To make icecream, you can pour that liquid nitrogen over a mix of milk, sugar and vanilla and stir. It looks great, as there the gas vapour goes all over the bowl and table. But you have to wear extra thick gloves and safety glasses though when you do it.
Q: What kind of gear do you wear when it is as cold as it is in Antarctica?
A: Lots! We wear thermals, long pants and jumper, over that we wear ski trousers or rubber pants and on top of that a thick anorak with a floating padding inside in case you fall over board. Then a woollen hat (beanie), a hard hat on top, rubber gloves with extra fluffy gloves inside. And also big woollen socks and rubber boots with a steel cap. We look very funny when we are all dressed up.
Q: Have you ever found something unnatural? For example, a starfish with a missing arm.
We have found a starfish with 4 arms – we called him “Mr Toast” because he looks exactly like a piece of toast. He comes naturally that way, but it looks funny. We have even made a note in our database – you can search for ‘Mr Toast’ and his photo will show up. Starfish often shed an arm when they feel attacked, but they usually can regrow them. It’s pretty nifty.
Q: Do you ever find unknown organisms?
A: Yes, we do and once we have identified and described them in a scientific paper, they have their own name.
Q: Do you like going on these long trips?
A: Yes, we all do. Being at sea is what we all love about our job. We see fascinating things and can be in very isolated places. But sometimes it’s nice to think about home, and we miss our friends, family and pets.
Q: What is the scientific name for shrimp?
A: All crabs, shrimps, prawns and lobsters are in a big group called Decapoda. Within that group, there are two smaller groups. One of them, the Dendrobranchiata, includes prawns. In the other group, called Pleocyemata, there are shrimps, crabs and lobsters. So, it’s kind of neat that shrimps are more closely related to crabs than to prawns! Prawns have three kinds of claws, and shrimps only have two!
Q: What is the scientific name for sea spider?
A: Sea spiders are in a group called Pycnogonida. They are not closely related to the spiders that you see on land.
Q: When you go trawling, what do you keep and what do you leave in the ocean? How do you decide?
To carefully answer our scientific questions, we need to have about 20 specimens of the same species. So first we need to know which animals are the most easily found, because we need to find them from many different places. We work on invertebrates (these animals have no backbone). So we try and find animals that are from an animal group we are interested in, for example nudibranchs (sea slugs), worms, sea stars, gastropods etc.
Q: What does this Porania sea star look like? Why is it so special? What scientific information will it provide?
Porania can be very colourful; it can be all shades from bright orange to a velvety red or even purple. There are photographs of Porania in the image gallery.
Q: How many miles have you crossed in the ship since you left?
As of today, its more than 3000 nautical miles.
Q: How are you all liking your trip so far?
A: Thanks for asking Jordon C, we all like it very much. The moment a trawl comes up we are all outside to see what came up that time. It’s like a big treasure chest coming up from the sea! But we have also time to see other things, we saw dolphins and pilot whales, we have time to read books and we are enjoying chatting to each other. You would think that it can be boring to be on a ship for so long, but it isn’t.
Q: Where do you store the preserved specimens you catch?
A: We brought all sorts of vials, test tubes and jars with us and we will first ship all these back to San Diego. Then some of them will be shipped on to other institutions around the world for study, like the Australian Museum.
Q: What is the exact process you take to preserve these specimens?
A: We decide what we want to do with the animal and then decide on the way we preserve it. We always assign a number to the animals and photograph them. Some soft-bodied animals like slugs are best preserved in formalin, and some hard-bodied ones like seastars are best kept in ethanol. But if we want to look at DNA, we need to have at least a piece stored in ethanol. Sometimes we take many samples from the one animal. All this information is entered into a database with the photograph. This makes it easier for us later to find the information and remember what the animal looked like in ‘real life’. Most of the time, animals loose their colours in those chemicals. You have probably seen jars like that in movies or in museums.
Q: You said it takes 30-40 minutes to drop the trawl net to the ocean floor. Why don't you put something heavy in the trawl net so it will go to the bottom faster?
A: Good question. The problem with doing that is that the net will then be especially heavy to bring up to the surface again. Or we’d have to somehow automatically dump the weights before bringing up the net, but that would be littering the ocean floor. The deeper the water is, the longer it takes to sample.
Q: Why doesn't your expedition go closer to tropical places? There might be more fascinating new creatures to find there.
A: There are still lots of things to discover in tropical waters too. But actually we know less about deeper colder waters.
Q: What is the smallest specimen you have found on this trip so far? How big is it?
A: The smallest so far would be a so-called “dwarf male” parasite that lives on a female parasite that is at least 100 times his size. We found these parasites inside the body of a feather star. The dwarf male parasite could only been seen under the microscope.
Q: Are the same preservative liquids used on every animal that you find?
A: No, we have to know what we want to do with the animal. Naomia will know how to answer your question now ;-)
Q: How long does it take to complete a trawl? Why don't you wait till the net is halfway down in the ocean to begin a trawl? That way you can catch more species like fish?
A: The time of a trawl depends on how deep we go. If you remember some action movies you will remember that even wires can snap when the weight or pressure on them is too much. We need to be careful with the wire that has our trawl net on it, we don’t want to lose it (they are very expensive and cannot replaced easily – we can’t just turn around and get another one). Since all this is heavy, it needs to be handled with a crane and some heavy machinery. We need to make sure that we don’t damage the engines and that people are safe. That’s why it has to be done fairly slowly. When we trawl in 100 m it takes about 50 min, but the deeper we go the longer it takes. Our last deep trawl down at 1000 m took 5 hours. Our trawl is designed to go along the bottom and catch the animals that live there. If we wanted to catch fish from midwater, we would use a different kind of trawl.