![shaka 60 gif.gif](https://files.peakd.com/file/peakd-hive/agmoore/eNIFXk2k-shaka206020gif.gif) This LMAC collage was inspired by a *YouTube* video of a sea urchin army: https://www.youtube.com/watch?v=D3W4OCnHyCs I had studied @shaka's amazingly beautiful underwater photo. ***@shaka's Photo*** ![ETeEQWJ Imgur.jpg](https://files.peakd.com/file/peakd-hive/agmoore/Xqm2Ahyp-ETeEQWJ20-20Imgur.jpg) All @shaka's pictures are impressive but this one was perfect. I was bereft of ideas until I saw sea urchins consuming kelp. Sea urchins have very sharp teeth. https://www.youtube.com/watch?v=B7aQrF3Vtfc These teeth will never need the attention of a dentist. Despite the fact that urchins chomp on rocks and shells, their teeth never become dull. As a matter of fact, the more they chomp, [the sharper](https://www.mccormick.northwestern.edu/news/articles/2019/09/research-reveals-self-sharpening-mechanism-in-sea-urchin-teeth-espinosa.html) the teeth get. As the teeth make contact with hard surfaces, material is selectively worn off. All the while the urchin's teeth continue to grow, so the lost material is perpetually replaced. Horatio Espinosa, of Northwestern University, compares it to sharpening a knife blade. https://www.youtube.com/watch?v=nI02svzU0Bw The urchin's five teeth work in unison and the jaw structure is referred to as Aristotle's Lantern. Aristotle described the mouth structure of the urchin as [*looking like a'"horn lantern'*](https://www.thoughtco.com/aristotles-lantern-2291609). ### Do They Live Forever? Almost. Urchins have one of the [longest life spans](https://today.oregonstate.edu/archives/2003/nov/red-sea-urchins-discovered-be-one-earths-oldest-animals) on earth, some observers have suggest they may have the longest life span. They don't seem to suffer senescence. Even very old sea urchins can reproduce and show no signs of aging. Their lives are likely to end when they are eaten by a predator. Unlike some animals (moths, for example), the sea urchin larval stage is very short. Here's a *YouTube* video showing time-lapse larval development. https://www.youtube.com/watch?v=HETAoq2wYPM The larvae feed for [about a month](https://today.oregonstate.edu/archives/2003/nov/red-sea-urchins-discovered-be-one-earths-oldest-animals) before becoming very small sea urchins. Sea urchins reproduce by releasing sperm and eggs into the water. While there are male and female sea urchins, no external sex organs distinguish the two. They look the same. ### What do they eat? Famously, they eat kelp. As a matter of fact, they eat so much kelp that, according to some [California marine scientists,](https://www.npr.org/sections/thesalt/2019/09/09/756929657/saving-californias-kelp-forest-may-depend-on-eating-purple-sea-urchins)their appetite for this algae is endangering the survival of purple kelp in the Pacific. However, sea urchins are omnivores that eat plant and animal matter alike. But as they eat, so are they eaten. ***Sea Otter*** ![Sea otter morro Mike Michael L. Baird 2.0.jpg](https://files.peakd.com/file/peakd-hive/agmoore/xnt8XBIV-Sea20otter20morro20Mike20Michael20L.20Baird202.0.jpg) *Image credit: "Mike" Michael l. Baird. Used under [CC 2.0 license](https://commons.wikimedia.org/wiki/File:Sea-otter-morro-bay_13.jpg)* Sea Otters eat [urchins, as do starfish, humans](http://tolweb.org/treehouses/?treehouse_id=4881) and the [spiny lobster.](https://oceanwildthings.com/2010/10/the-california-spiny-lobsters-role-in-the-ecosystem/) ### Sea Urchin Defense Sea urchins use their spines to defend themselves. Wounds from these can be painful, or fatal. Some species of sea urchin are [venomous](https://www.medicalnewstoday.com/articles/319360#what-is-a-sea-urchin-sting) and at least one, the flower sea urchin (*Toxopneustidae*) can be highly toxic. ![Flower Urchin_Toxopneustidae_12_cmSamuel Chow 2.0.png](https://files.peakd.com/file/peakd-hive/agmoore/iRBFgrHv-Flower20Urchin_Toxopneustidae_12_cmSamuel20Chow202.0.png) *Image credit: Samuel Chow. [CC 2.0 license](https://commons.wikimedia.org/wiki/File:Flower_Urchin_(Toxopneustidae)_(12_cm).png)* ### Types of Sea Urchins While I have written about spiny sea urchins, there are other types of urchins, including sand dollars and Spatangoida. ***Eccenteric Sand Dollar*** ![Eccentric_sand_dollar.jpg](https://files.peakd.com/file/peakd-hive/agmoore/jVjtjN2N-Eccentric_sand_dollar.jpg) *Image credit:D. Gordon E. Robertson CC [3.0 license](https://commons.wikimedia.org/wiki/File:Eccentric_sand_dollar.jpg)* ***Spatangus Purpureus*** ![Spatangus purpureus_rob Rpillon 3.0.jpg](https://files.peakd.com/file/peakd-hive/agmoore/YyfDvhQT-Spatangus20purpureus_rob20Rpillon203.0.jpg) *Image credit: Rpillon [CC 3.0](https://commons.wikimedia.org/wiki/File:Spatangus_purpureus_rob.jpg)* ![border creative.jpg](https://files.peakd.com/file/peakd-hive/agmoore/uyKYNCZG-border20creative.jpg) I'll end this excursion into the world of the sea urchin by linking to an amazing *National Geographic* [video](https://video.nationalgeographic.com/video/news/0000015a-fd24-dce2-ad5f-fdee88c20000) of a carrier crab, carrying a red sea urchin. Apparently this arrangement works for both species. The crab gets [cover](http://ourworldunderwater.com/wp-content/uploads/2018/01/DIYI-Carrier-Crab.pdf) from the spiny sea urchin, and the sea urchin gets to move to new areas where it can feed and also reproduce. ***Carrier Crab with Red Radiant Sea Urchin*** ![Carrier Crab_Dorippe_frascone_with_Red_Radiant_Sea_Urchin_Astropyga_radiata.jpg](https://files.peakd.com/file/peakd-hive/agmoore/y5wEw41G-Carrier20Crab_Dorippe_frascone_with_Red_Radiant_Sea_Urchin_Astropyga_radiata.jpg) *Image credit: Sylke Rohrlach. [CC BY-SA 2.0](https://commons.wikimedia.org/wiki/File:Carrier_Crab_(Dorippe_frascone)_with_Red_Radiant_Sea_Urchin_(Astropyga_radiata).jpg)* ### My Collage This collage went through so many interations (don't I always say that?). The artists in the #LMAC community have a strategic method. My method is completely intuitive. I start with an idea and then muddle along. Eventually the collage finds itself. Here are a few steps from this week: ![shaka 60 1.jpg](https://files.peakd.com/file/peakd-hive/agmoore/BIgmyemR-shaka2060201.jpg) It began with a sea urchin, taken from *Paint 3d* that I warped with *GIMP*. Then I went for hermit crabs, an octopus and sea urchin, also taken from *Paint 3D* : ![shaka 60 2.jpg](https://files.peakd.com/file/peakd-hive/agmoore/FdmcnLuy-shaka2060202.jpg) Sea horses were part of the scene for a while, and there was a lot of warping (thank you, @quantumg) and rippling (using *GIMP*). Finally, as late night approached I thought of how @muelli uses drama in his collages. And of course, sea urchin teeth were uppermost in my mind. After many false starts, this happened: ![shaka 60 gif.gif](https://files.peakd.com/file/peakd-hive/agmoore/Xvhf3EfW-shaka206020gif.gif) I used the warp function on *Gimp* to create the explosive effect. I drew the teeth on the fish, once again by using *GIMP*. All elements in the collage, kelp,fish, sea urchins, came from *Paint3D*. ![border creative.jpg](https://files.peakd.com/file/peakd-hive/agmoore/uyKYNCZG-border20creative.jpg) Thank you @shaka for the headache, for the hunting and thinking--a creative journey that always allows me to grow. I've looked at some of the other entries. What works of art this week. Truly inspired. To my readers: please take a look at @shaka's [blog](https://peakd.com/hive-174695/@shaka/let-s-make-a-collage-a-contest-for-all-creatives-in-the-hive-round-60-154-hive-in-this-round-s-prize-pool) for a creative feast. Join our growing LMAC community. We have the most congenial environment and a [school](https://peakd.com/hive-174695/@lmac/the-lmac-school-acquire-the-skills-to-bring-your-ideas-to-life) with our brilliant teacher, @quantumg, who amazes me with his patience. ![lmac graphic3.jpg](https://files.peakd.com/file/peakd-hive/agmoore/wYz6Csd6-lmac20graphic3.jpg) *Thank you for reading my blog* ![fox and squirrel friendsgif.gif](https://files.peakd.com/file/peakd-hive/agmoore/A12jWjd7-fox20and20squirrel20friendsgif.gif) *Hive on*

RE: Senderismo en Bicicleta [ESP | ENG]