Spider Crab Watch

Frequently asked questions

1. What does "moulting" means and what is an "aggregation"?
2. What questions is the research seeking to answer?
3. Why are timelapse cameras useful tools to collect data and understand spider crabs better?
4. Why are there many photos without spider crabs and without animals?
5. What else is being done to study spider crabs?
6. What do I do when different species of animals are present in a photo?
7. What do I do if there is an animal that isn't in your list?
8. How to tell if a spider crab has moulted?
9. Can I review the images I have classified?
10. What do I do if I made a mistake?
11. What if there is an image I find interesting and want tell the team about and be able to find easily afterwards?
12. What do I do if I want to ask a question not listed above?

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1. What does "moulting" means and what is an "aggregation"?

Spider crabs come in massive numbers together mostly in the winter time in Port Phillip Bay(near Melbourne, Victoria, Australia) and in different parts of the Great Southern Reef (the Southern coast of Australia). They are on a mission: in order to grow bigger, they need to extract themselves from their shells, expand their soft body and grow a new shell. This process is called moulting. Whilst the spider crabs are waiting for their new shells to harden, they are soft and vulnerable to predation. This is why they come together in such big numbers forming what is called an aggregation - to seek protection in numbers. Spider crabs also form aggregations at other times of the year for unknown reasons!

2. What questions is the research seeking to answer?

Very little is known about spider crab ecology and about their aggregations. Our research team, which at the moment focuses on the spider crab aggregations in Port Phillip Bay in Australia, has so many questions! We are using both traditional and citizen science to solve spider crab mysteries. Here's what we don't know:

• where spider crabs come from and whether they travel from Bass Strait (outside Port Phillip Bay) or whether they live in the Bay;
• how many spider crabs are out there throughout their range (the southern coast of Australia, called the Great Southern Reef) or in their winter aggregations, and if and how these numbers vary through time;
• what signals they use to know when it's the right time to come together and moult. It is thought that perhaps temperature or moon phase could play a role, but we don't really have evidence of this at the moment;
• how do they choose where to go? in Port Phillip Bay, there have historically been aggregations under piers on the Mornington Peninsula but there is anecdotal evidence that they can come together in various places in the Bay. In the past two years, they have been seen aggregating at those piers, and the reason for that is unknown;
• why do they gather at other times of year. Aggregations are sometimes seen outside of winter, they happen randomly in time and space, and so far, we don't know the purpose at these aggregations;
• what are the aggregations made of (mostly males? mostly females? a mix? what kind of sizes?);
• how long do the aggregations last and if and why the duration of the aggregation vary through time and space;
• what is the role of spider crab aggregations for the broader environment, including spider crab predators.

3. Why are timelapse cameras useful tools to collect data and understand spider crabs better?

Spider crabs and their aggregations are surrounded with mysteries. It is difficult to study spider crabs because whilst their aggregations usually happen in the winter months (May-July), they can be short-lived and it is not easy to predict when and where they will take place. Timelapse cameras are useful tools to monitor spider crabs and their aggregations because they can stay in place for a few weeks at a time and take photographs that allow us to detect both spider crab activity and other marine life in the environment, including spider crab predators. They are non-intrusive, which means that they don't create disturbances to marine life and their environment. It allows us to determine how long aggregations last when they occur, how the number of spider crabs in aggregation varies from day to day, when moulting is taking place and how the activity of predators and other marine life varies with spider crab activity.

4. Why are there many photos without spider crabs and without animals?

This year (2022), timelapse cameras were initially deployed at two locations on the Mornington Peninsula in Port Phillip Bay - Rye and Blairgowrie piers. We chose these locations because spider crabs have regularly formed aggregations there in winter for many years. However, this year, they aggregated in different locations and only a few spider crabs were detected at Rye and Blairgowrie piers. The main accessible location where they aggregated was on the Bellarine Peninsula and cameras were deployed when the aggregation was accessed by the research team.
Timelapse cameras take photos every five minutes during daylight hours, which explains why a lot of images don't have spider crabs or other animals in them. Your help is invaluable to filter out images without animals in them. In the future, we're hoping to use your classifications to train an AI to filter out these images automatically.
Photos that don't contain spider crabs but contain other animals are still very useful to gain baseline data on the marine life that is around at that time of year and to help us make comparisons between sites with and without spider crab activity.

5. What else is being done to study spider crabs?

For the first time this year (2022), we used a range of methods to study spider crabs in an aggregation, including:

• performing video transects to estimate spider crab and predator densities;
• measuring and sexing spider crabs;
• attaching little acoustic tags to find out about spider crab movements after they leave the aggregation.

6. What do I do when different species of animals are present in a photo?

Zooniverse allows you to label different species in the same image, so mark every species you can identify before clicking "Next".

7. What do I do if there is an animal that isn't in your list?

Occasionally, there will be a few species of fishes or invertebrates (animals without a backbone) which will not be listed because only one or very few photos contain this specific animal. If it looks like a fish, click on "Other fishes (not listed above)" and if it is an invertebrate, click on "Other invertebrates (not listed above)"

8. How to tell if a spider crab has moulted?

Spider crabs which have moulted are much brighter than spider crabs which haven't moulted yet. The latter usually have duller colours and shells that can be covered with algae. Spider crabs that haven't moulted yet can miss quite a few legs as well.

9. Can I review the images I have classified?

Yes! You can navigate back to your classifications for Spider Crab Watch and any other projects by clicking on your username (top right corner of your screen when you're logged in to Zooniverse) and then "Profile" (in the dropdown menu) and then "Your stats" on your profile page. There you will see images for each project you've made classifications for and the number of classifications you've made for each (in the top right corner of individual project image)

10. What do I do if I made a mistake?

You can correct your classification any time BEFORE submission by clicking the "Back" button. You can delete any of the circles and boxes you have drawn by clicking on the cross beside these individual markings. You can also easily adjust the size of the markings. When you get to the task asking you to identify other animals, you can delete an wrong identification by finding the names in the blue boxes in the bottom of the images and clicking on the cross beside them. Unfortunately, you can't make any changes after an image has been submitted but don't worry too much as each image will be analysed by multiple volunteers.

**11. What if there is an image I find interesting and want tell the team about and be able to find easily afterwards? **

When you finish your classification, you'll get a summary of your responses and drawings, you can click on "Talk", at the bottom of the classification, and add comments there. You can also favorite an image (by clicking on the heart beneath the image). You can navigate back to it later by clicking on your username (top right corner of your screen when you're logged in to Zooniverse) and then "Favorites".

12. What do I do if I want to ask a question not listed above?##

You can use the "Talk" boards to reach out to the team. You can search questions others have asked and see if you can find the answer that you are looking for, but if not, feel free to create a new discussion (click on the relevant forum under “Help”). The scientists in the research team will get back to you and answer your questions.