Lodewijk van Walraven

@lodewijkw.bsky.social

60 followers 59 following 26 posts

Marine ecologist at Wageningen Marine Research
jellyfish expert, diver, photographer. Plankton enthusiast.
Sites: zooplankton.nl, plankton.photography

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Jul 04, 2024 at 11:17 UTC

This female Japanese shore crab in the Wadden Sea was busy releasing her babies into the water! You can see the tiny zoea larvae being released into the plankton where they will live for several weeks and many will be eaten. The few survivors settle on the bottom again.

1 replies 2 reposts 16 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Jul 04, 2024 at 07:00 UTC

We saw a wide range of fish species during our dive in the Wadden Sea off #Texel such as tompot blenny, whiting, rock gunnel, longspined bullhead, fivebeard rockling and even a seabass!

0 replies 0 reposts 0 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Jul 03, 2024 at 20:41 UTC

The huge mussel spatfall in the Wadden Sea caused a feeding frenzy of sea stars and crabs! Likely within a few weeks most of the mussels will be eaten or washed away by the tides.

0 replies 1 reposts 2 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Jul 03, 2024 at 20:36 UTC

Diving in the Wadden Sea is rarely possible because of the extremely turbid conditions, but last week we could finally dive again due to very calm conditions. We discovered that every available surface was covered by a thick layer of juvenile mussels "seed"!

1 replies 1 reposts 7 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Feb 07, 2024 at 16:04 UTC

Interested in pursuing a PhD in zooplankton ecology? We have three PhD positions available! The PhDs will study different aspects of zooplankton ecology in a changing North Sea, based at
NIOZ with additional supervision by us at WMR.
Info: workingat.nioz.nl/o/...

0 replies 1 reposts 0 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Dec 19, 2023 at 09:42 UTC

This week we @WURmarine are trialing the use of the Plankton Imager on RV Tridens during the ICES herring larvae survey in the English Channel. Continuous sampling of zooplankton composition at 1000s of images per min. First images look great! #Plankton #MarineLife.

0 replies 1 reposts 6 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 29, 2023 at 10:33 UTC

The Norway Lobster Nephrops norvegicus also has planktonic larvae which grow quite big before settling. They are instantly recognisable because of their huge spoiler-like telson! #Plankton #MarineLife

0 replies 1 reposts 15 likes

Reposted by Lodewijk van Walraven

Todd Oakley @ostratodd.bsky.social
[ View ] Nov 29, 2023 at 02:47 UTC

Beautifully written piece in the NYT about the latest paper from @nikohensley.bsky.social describing incredible and coordinated blue-waves of bioluminescence in Panamá #evolution 🧪🦑 #invertebrate www.nytimes.com/2023/11/28/s...

0 replies 4 reposts 13 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 28, 2023 at 07:45 UTC

zooplankton.nl/en/diversity...

0 replies 0 reposts 0 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 28, 2023 at 07:45 UTC

Check out my website for a video of how they touch the substrate: www.youtube.com/watch?v=fwIA...

1 replies 0 reposts 1 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 28, 2023 at 07:00 UTC

When the barnacle larva transforms into its final stage, the cypris larva, it is ready to settle. It swims around sniffing for other barnacles and a nice rock to settle on. Once found it glues itself to the rock and is stuck forever! #Plankton #MarineLife

1 replies 1 reposts 7 likes

Reposted by Lodewijk van Walraven

Jeff Day @jeffday.bsky.social
[ View ] Nov 28, 2023 at 04:48 UTC

yooo, new true jelly (scyphozoa) dropped! santjordia pagesi, based on two specimens collected 8 years apart from the sumisu caldera south of japan. genetic analysis places it in the ulmaridae family but it's unique enough to merit its own subfamily. 🧪🦑

mapress.com/zt/article/v...

4 replies 12 reposts 49 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 27, 2023 at 07:00 UTC

Barnacles have larvae in the plankton as well! The nauplius larva reveals their crustacean origin - it looks similar to the copepod nauplius larva but can be recognised by the two "horns" and the way it swims rowing its appendages. #Plankton #MarineLife

0 replies 3 reposts 22 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 26, 2023 at 07:00 UTC

Phyllosoma larvae are quite rare in the plankton and I only found a few, like this one I found on a Mediterranean holiday. Here imaged using an old school (100+years) microscopic illumination technique called Rheinberg Illumination. #Plankton #MarineLife

0 replies 15 reposts 71 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 25, 2023 at 07:00 UTC

Perhaps the weirdest and coolest crustacean larvae are the thin, flat and transparent Phyllosoma larvae of spiny lobsters, slipper lobsters and relatives. They can often be seen riding on- and eating jellyfish! #plankton #MarineLife

1 replies 11 reposts 56 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 24, 2023 at 07:00 UTC

After moulting a few times as zoea larva the crabs enter their final larval stage; the megalopa which already looks like a tiny adult crab, which will settle on the seafloor. These crab larvae are voraceous predators of the plankton! #plankton #MarineLife

1 replies 1 reposts 20 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 23, 2023 at 07:00 UTC

This is the cutest crab larva of all: the larva of the pea crab Pinnotheres pisum! It has only small spines and is already as round as the adults. #plankton #MarineLife

1 replies 5 reposts 25 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 22, 2023 at 17:12 UTC

Here is another zoea larva of a brackish water crab ( Rhithropanopeus harrisii). This one has super long spines!
#plankton #MarineLife

0 replies 1 reposts 8 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 21, 2023 at 19:59 UTC

Yes! 👋 Lots of wonderful shots on your instagram!

1 replies 0 reposts 1 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 21, 2023 at 15:47 UTC

Perhaps this paper has the answer? www.researchgate.net/publication/...

0 replies 0 reposts 3 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 21, 2023 at 15:24 UTC

Cool! Must be challenging to assign these larvae to an adult taxon since you can't use DNA like for extant fauna.

1 replies 0 reposts 1 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 21, 2023 at 08:00 UTC

Crustaceans such as crabs, shrimp and even barnacles often have a larval stage in the plankton. These can have bizarre shapes! This is a zoea stage larva of a crab, which has long spines to decrease its chance of being eaten by predators. #plankton #MarineLife

1 replies 6 reposts 25 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 21, 2023 at 07:00 UTC

Many bottom dwelling organisms like crabs, worms, sea stars and barnacles have larval stages in the plankton. Carried by currents the larvae can be transported to other areas. Often the larval stage does not look like the adult at all! Can you guess which is which? #MarineLife

4 replies 12 reposts 36 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 20, 2023 at 21:58 UTC

I am a marine biologist studying zooplankton using innovative tools like in-situ imaging devices and genetics. In my spare time I like to spend hours at the microscope to capture images of the beautiful and bizzarre planktonic creatures. I'll try to share an image every day!

0 replies 0 reposts 2 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 20, 2023 at 20:49 UTC

#addOcean

0 replies 0 reposts 1 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 19, 2023 at 13:13 UTC

Met de app sky follower bridge kan je mensen die je volgt op Twitter toevoegen, werkte aardig goed.

1 replies 0 reposts 2 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 19, 2023 at 08:22 UTC

Thanks for the invite!

0 replies 0 reposts 1 likes

Lodewijk van Walraven @lodewijkw.bsky.social
[ View ] Nov 18, 2023 at 18:03 UTC

I created a short film showing the diversity and beauty of the zooplankton! It shows examples from a wide range of taxa from copepods to the weirdest larvae. Watch full version in beautiful 4K!
Youtube: youtu.be/2OtAV6T2SLg
Vimeo: vimeo.com/755893528

1 replies 2 reposts 6 likes