Impurest's Guide to Animals #157 - Trembling Sea Mat
By ImpurestCheese 19 Comments
January lags on being boring and grey as per bloody usual. Last week we looked at an animal, the Buoy Barnacle, which seemed boring and grey but turned out to be quite exciting. This week we look at something that could be an animal, or a plant or maybe a mineral, hope you guys enjoy…
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Issue #157 – Trembling Sea Mat
Kingdom – Animalia
Phylum – Bryzoa
Class – Gymnolaemata
Order – Ctenostomadia
Family – Victorellidae
Genus – Victorella
Species – pavida
Related Species - Trembling Sea Mats are one of 4000 bryzoans or moss animals, so named for their plant like appearance (1)
Range - Trembling Sea Mats are found in coastal waters around Europe and the Middle East as well as the Eastern Seabord of the United States.
Animal, Vegetable or Mineral
Individual Trembling Sea Mats are tiny animals, no more than half a millimetre long. As a colonial animal however, they often gather in groups that resemble mossy carpets on the stones and kelp fronds that they grow on. Individual members of this colony are called ‘zooids’ and are specialised to certain roles within the colony, although they act independently from each other and are not part of a hive mind like ants or bees. All zooids form a cystid from organic materials produced by the epidermis, which the feeding apparatus, digestive and nervous system sits inside (2).
Those zooids responsible for providing food for the colony are the autozooids, and they possess a crown of tentacles called a lophophore, which snatches microscopic organisms from the water and brings them inside the cystid where the food is digested and the energy diffused across the colony. Predators of the Trembling Sea Mat include molluscs and crabs, and their grazing triggers the colony to grow more defensive spinozooids to fend off future attacks. Should two colonies of Trembling Sea Mat meet, they decide to grow in opposite directions since it takes less energy to expand into unclaimed territory than to fight out ‘turf wars’ to determine which colony is dominant.
While the individual zooids will have a defined gender, the colony that makes up the Trembling Sea Mat is a hermaphrodite. During reproduction, the female’s zooids released unfertilized eggs which are captured by male autozooids, fertilized and then released (2). Upon hatching the larval Trembling Sea Mats swim around feeding on other members of the plankton before spinning a cocoon and sinking to the sea bed to mature into an adult zooid. This single unit will effectively clone, relying on stockpiled energy from its larval feeding to support itself until it expands into a colony.
Ecology 101: A Guide to Environmental Mechanics #16 - Photosynthesis in Animals
A few issues ago @ficopedia asked the following: Is a Sea Anemone a Plant or an Animal
The answer is that sea anenome’s are animals that are closely related to corral, jellyfish and hydrozoans. That said, some such as the Green Surf Anemone (Anthopleura xanthogrammica) do have photosynthetic algae living in their cells that do provide their host animal with energy in return for protection from grazers and a permanent place to live. Such an arrangement is helpful for animals that live in tidal environments like the anemone, since its food supply is dependent on whatever is swept in at high tide and what species can survive low oxygen levels and potential desiccation when the tide retreats.
This partnership between algae and in some cases bacteria and their animal hosts probably first evolved by accident. The majority of animals that have photosynthetic organisms living within them are filter feeders, and it is highly likely that the animal caught its future partners which were able to avoid being destroyed when they were consumed. This process can be seen in the Flatworm Symsagittifera roscoffensis whose larvae are free swimming hunters (3), and who often feed on microscopic photosynthetic organisms at the ocean’s surface. On maturation, the Flatworm ceases to be an active predator and switches over to feeding almost entirely to using solar energy.
Such energy gathering comes at a cost, the flatworms have to sit out in the open at the ocean’s surface where they are at risk of predation, something they avoid by forming giant swarms of worms that resemble seaweed floating just under the surface. This highlights one common problem that links all animals that rely fully or partially on photosynthetic allies, they are restricted to very shallow water where they face stiff competition from marine plants and increased unwanted attention from both predators and grazers.
The Eastern Emerald Elysia (Elysia chlorotica), a marine sea-slug, solves this problem through kleptoplasty, who steals the genes from the algae Vaucheria litorea that it feeds on. After consuming the algae the slug incorporates the chloroplast genes into its body, which ironically is leaf shaped. At first the slug needs to feed almost constantly to keep its supply of chlorophyll intact, but after a few feedings the chloroplasts it has stolen can last for up to ten months in the slug’s body. While the slug does need to keep feeding, it can survive for up to a month without feeding, relaying on just the energy it manufactures using the chloroplasts it steals from its food (4).
While the majority of photosynthetic animals invertebrates, there is at least one vertebrate, the Spotted Salamander (Ambystoma maculatum) that does use photosynthetic organisms to aid in its growth in its larval tadpole stage (5). This time the algae finds its animal host, with the plant colonising the eggs of the salamander in the pools the adults lay them in. Because of the stagnant nature of their nursery environment, upon hatching the larval tadpoles take oxygen produced by the algae as well as glucose to speed their growth into their adult form. While the salamander can survive without the algae, the reverse is not true, with their plant allies remaining in a cyst like form until it senses the chemical cues of the developing embryo’s waste products being released into the water.
Bibliography
1 - www.arkive.org
2 - Ruppert, E.E.; Fox, R.S. & Barnes, R.D. (2004). "Lophoporata". Invertebrate Zoology (7 ed.). Brooks / Cole. pp. 829–845
3 - https://www.newscientist.com/article/2078532-green-worms-create-a-superorganism-that-becomes-a-giant-seaweed/
4 - Christa G, Zimorski V, Woehle C, Tielens AG, Wägele H, Martin WF, Gould SB (2013). "Pastid-bearing sea slugs fix CO2 in the light but do not require photosynthesis to survive". Proceedings of the Royal Society B. 2815 -
5 - http://nautil.us/blog/the-salamander-that-has-photosynthesis-happening-inside-it
Picture References
1 - http://static.panoramio.com/photos/large/80781257.jpg
2 - http://www.marlin.ac.uk/assets/images/marlin/species/web/o_vicpav.jpg
3 - http://i.dailymail.co.uk/i/pix/2016/02/25/11/318B85DD00000578-3463588-The_worm_is_found_in_shallow_water_on_sand_beaches_at_certain_si-a-39_1456398942988.jpg
4 - https://blogs.scientificamerican.com/brainwaves/files/2013/12/Elysia_chlorotica_1-300x296.jpg
5 - http://static.nautil.us/2786_fb3f76858cb38e5b7fd113e0bc1c0721.jpg
Talk about being one with your garden, perhaps such organisms as the ones mentoned above could one day help reduce the amount of land needed for agriculture, with humans making their own solar powered snacks. Next week we celebrate Chinese New Year although I’m not sure that’s anything to crow about, but until then make sure to critic, comment and suggest future issues as well as making sure you check out past issues in Impurest’s Bestiary.
Many Thanks
Impurest Cheese
Want more IGTA? If it’s something that looks like a plant you’re after, click here to meet the grotesque Gorgonocephalus. Or for something that also looks like a plant, click here to see the really Stinky Squid.
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