The short and sweet of horseshoe crab spawning

You may have heard about the phenomena of horseshoe crab spawning … but, do you really know what’s going on? It’s when hundreds of thousands of these ancient arthropods (dating back 400 million years!) make the journey to low-energy sandy beaches along the Atlantic coast, predominately along the Mid-Atlantic region (highest concentration found along the Delaware Bay), around the time of the full and new moons of May and early June to spawn. Here’s the distilled version of the horseshoe crab spawning saga complete with the words you need to know (i.e., “pedipalps” and “satellite” male) if you want to be considered a horseshoe crab expert. Who doesn’t?

https://www.flickr.com/photos/beachchairscientist/

https://www.flickr.com/photos/beachchairscientist/

  1. Journeying from intertidal and deeper waters, male horseshoe crabs arrive near the beach waiting for females.
  2. As the females come closer to shore, males attach to the female’s abdomen. The extra claw, or “pedipalps”, is what the male uses to attach itself to the females.
  3. Not just the one … but, many “satellite” males follow the conjoined pair.
  4. The females dig a depression about 5 to 30 centimeters deep in the upper part of the beach and deposit the clusters of eggs.
  5. External fertilization occurs – Allows for a little extra competition from the “satellite” males!
  6. Repeat steps 1 through 5 multiple times per season, laying 3,650 to 4,000 eggs in a cluster (usually an estimated 88,000 eggs annually!).
  7. In 2 to 4 weeks after fertilization, planktonic larvae hatch from the eggs. Some slow moving larvae may even winter within the nests and hatch out the following spring.
  8. After hatching, larvae swim for about six days before they relax in shallow waters to molt into their first juvenile stage in approximately 20 days.
  9. For the first two to three years of life horseshoe crabs molt many times over, growing a quarter of their size each time. Once sexual maturity is reached they slowdown their molting to once per year.
  10. Horseshoe crabs mature around 10 years of age (or 17 molts) and are known to live to be approximately 20 years of age.

For more information on horseshoe crabs and “99 reasons I am in Limulus Love” check out my horseshoe crab page here.

10 tips for a successful beachcombing trip

Pick up that clump! You never know what you'll find.

Pick up that clump! You never know what you’ll find.

It’s my favorite time of year. This is the best time to explore the beach. It’s still sunny and warm, there are frequent storms (you’ll see why that matters later), and there are few people on the beach. For another six weeks along the mid-Atlantic (before it gets too cold), I encourage you to spend some time getting to know your local shoreline. Here are 10 tips for a successful beachcombing trip.

10. What to bring. Here is a list of some items you may want to remember so you’re prepared for any situation.

  • Often the beach is considerably cooler than inland so bring layers. You may want to wear hiking pants and bring a zippered sweatshirt so you’re equipped with lots of pockets for some other items that might be essential.
  • Make sure to have some appropriate soles. Sure it’s our instinct to be barefoot, however if you want to venture out along the jetties or rocks make sure you have some old sneakers or those water shoes with some decent grip (After all, you don’t want to ruin your adventure with a puncture to some sharp object). Also, the water might be a little cooler than you’d prefer and some good foot cover will allow you to wade into a tide pool.
  • Make sure to have a watch.
  • Even during the off-season the sun is shining and is strong enough to give you a burn. Make sure to bring along a hat, sunglasses, and sunscreen.
  • It’s always a good idea to bring a shovel, grabber sick, or even a metal detector so you can gently investigate inside crevices and below the sand.
  • You are going to want to cherish the moments so find that camera and try to make a neck strap so it’s always handy. You can take pictures of items you find and want to learn about later. You’ll also want to catalog those smiles in the sun.
  • Take along a small (i.e., not heavy) identification book so you can learn more about what you find while on your outing.

9. Be hands free. One more item that you’re going to love me for suggesting is a backpack. This way you can investigate a little bit further from your base and your items are quickly at your disposal.

8. Leave important items behind. Don’t ruin the day by losing a credit card or your phone. If you’re active and in the moment you might lose something and it’s going to be difficult to retrace your steps. I won’t say “I told you so”. On the same note it’s important to leave animals, plants, rocks, and seashells where you find them. If you want to have a little bit of the beach in your home check out these great books by Josie Iselin.

7. When to go. To get the optimum experience for beachcombing you’ll want to check on when low tide is at your beach spot. The best time to go beachcombing is 2-3 hours prior to low tide or an hour or so after (This is why a watch is important, you don’t want to get stuck on  shoal during high tide). Many intertidal animals live under the water in the sand during high tide, but come out to play (and seek out food) during low tide. If you can time it so you get to check out the beach after a big storm you’ll be in for a real treat. The strong wind and wave action of storms will wash up a fossils, bones, seaweed, and lot of other interesting treasures from the ocean floor. Also, keep in mind that dawn and dusk are difficult times to identify beach treasures. Although this is a great time to spot birds as many fish tend to come up to the surface at these times.

6. Where to go. My favorite spot to beachcomb is the Stone Harbor Point in NJ, but it’s not always easy for me to get there these days. I like to remind myself from time to time that I don’t need an ocean to beachcomb. There is a lake and creek in my neighborhood and these spots are a great place to spend the afternoon. After all, these waterways eventually lead to the ocean.  No matter where I decide to spend some time beachcombing I always make sure to note the general water quality.

5. Be careful. This is just a reminder to not tamper with obviously dangerous items. Fish hooks, metal canisters, and needles often wash up on the beach. While I am going to also suggest doing your part and picking up marine debris it’s also a good idea to err on the side of caution and when poking around. Also, some rocks look very steady but it’s important to be aware of your surroundings. If you are feeling like having an adventurous day it’s might be a good idea to make sure you have someone else with you. One last thing about being careful,even though the dunes might look like an interesting place to check out – it’s important to know that those grasses are incredibly brittle and can crack easily. It’s also against the law to walk on the dunes. The dunes are an important part of the beach ecosystem as they protect our homes from storm surge.

4. Leave it be. Each rock that you turn over is part of an ecosystem. A rock might be an essential part of an animal’s home as it helps pool water during high tide. Rocks also protect them from predator as well as the sun. It’s important to always remember to not take animals out of their natural setting – especially if you see them in a tide pool. Many animals are naturally attached to rocks for survival and you could be risking their survival.

3. Play. You might not want to go home, but you also might be in the company of some people that just don’t have a very long attention span. Even more frustrating is repeating the phrase, “No, you cannot go in the water today” over and over again. Build a sandcastle. Look to the horizon for dolphins or porpoises. Make a sand angel. Look up to the sky for cloud animals. Check out my ebook for other beachcombing adventures.

2. Bag it and track it. It’s always nice to be prepared to be able to do your part. I prefer to take along a hefty canvas bag that can fit in a backpack so I can tote marine debris back to a garbage can. You might even try to acquire one of these nifty bags with holes for sand to percolate through from the Green Bag Lady. When you head back to the car you can even do some citizen science and log your marine debris on the Marine Debris Tracker.

1. Don’t expect too much. It’s important to remember to relax and respect the area you are exploring. All of the ideas above are simply suggestions and ideas to ensure you get the most out of  a beachcombing adventure. Please don’t hesitate to share your favorite stories, spots, and other ideas for a great day. You can comment below of email me at info@beachchairscientist.com.

Getting to know three … Malacostracan edition

Ever know instinctively that some animals are ‘related’ and just can’t pinpoint their similarities? On the third day of every month I explain three features that are common among three animals of a certain group. Of course, generally each group has more than three representatives and even  many more similarities and then even more differences, but I am going to choose three similarities that link threes to keep it simplified. This month is focused on the shrimp, the lobster, and the crab – all crustaceans, but more specifically all are members of the largest of the six classes of crustaceans known as the Malacostraca class. (Need a refresher on the trusty mnemonic device for classification? Click here.)

Check out ‘Getting to know three … Echinoderm edition’.

Holy, mole(y) crab!

Mole crabs are recognizable decapods with their barrel-shaped bodies and a grey colored exoskeleton and known to many of us as ‘sand fleas’. We often only see them for a wee bit when a wave (or curious hand playing in the sand) dislodges them and they quickly scurry back under the sand. These clawless crabs are not biting fleas and are fairly harmless member of the crustacean group.

Let me tell you what makes the mole crab a critter I can get excited chatting up during a day  at the beach. First, is that as the tideline goes in and out during the day, so do the mole crabs. Their preferred home is to be buried under the sand right at the tideline. Also, rather fascinatingly, mole crabs only move backward! They use their back legs to bury themselves under the sand as their head goes later.

They depend on the action of the ocean to filter them loose plankton and organic debris. They grab the particles by keeping their antennae at the sand surface (which is why their head goes in last as they bury themselves). They also use gills to take oxygen out of the water to breather, just like other crustaceans. During the summer you may see a female carrying one with eggs on her underside or near the legs. The orange eggs have just been fertilized while the darker grey eggs are ready to hatch. Male mole crabs are smaller than females, only reaching about half an inch in length, while females are typically an inch long.

Mole crabs are also a very popular form of bait for surf fishermen.  There are ten species recognized throughout the world, but two are most common on the eastern Atlantic and Gulf coasts, Emerita talpoida or Emerita benedicti.

Image (c) NJ SeaGrant

“The Timeless Traveler” a new documentary by River Bank Studios

According to Jason Peters from Filmmakers for Conservation, “The film Timeless Traveler – The Horseshoe Crab is a film about what some consider to be the world’s most spectacular scientific breakthrough that could rewrite the pages of medical history. It is an appeal for the conservation of a unique species and aims to achieve a widespread public awareness and appreciation of Horseshoe Crabs throughout India and the world.”

New ‘marine life encyclopedia’ launched

I think there might be another great bookmark to add to your ocean facts files! Please spend some time reviewing this great new resource, a marine life encyclopedia, compiled by Oceana. Over 500 creatures, places, and concepts can be explored. The pictures are bright and colorful and the information is up-to-date and easy to digest. It seems fantastic if you want a quick answer to a question.

Even if you think you know all the answers, test yourself with this Ocean IQ quiz!

The content on the marine life encyclopedia site has been licensed to Dorling Kindersley, one of the world’s leading educational publishers.

It’s as easy as A, B, Sea: H for Horseshoe Crab

 

Horseshoe crabs are an arthropod more closely related to spiders and scorpions than crabs and lobsters. They have a three part body: prosoma (head), opisthosoma (heavy shell with legs under it) and the telson (tail). This amazing body structure has been unchanged for over 200 million years. Interestingly enough, this is this Beach Chair Scientist’s favorite animal and there have been numerous posts about Limulus polyphemus. Read more here.

 

How do sea spiders distribute nutrients throughout their bodies?

If anyone has ever come upon a sea spider you immediately think – where are its guts and stuff? huge-sea-spiderThe answer is that their stomach, intestines and reproductive parts are housed within the sea spider’s legs. The animal breathes and manages waste by direct diffusion along the surface of it’s bodies. They can be a foot across – but, most types are barely more than 0.05 of an inch across! They do have a global distribution.

Sea spiders are not in the same exact family as other spiders. However, the sea spiders and terrestrial spiders are in a class together…along with one other creature, Horseshoe Crabs! Yup, horseshoe crabs are more directly related to spiders than other types of crabs.

Image (c) sethwhite.org

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