Urchins and Seagrass/Macros

[beefchicken31]

Will urchins, in particular the black longspine, eat seagrass or macro algaes?

 

[graveyardworm]

Yes most commonly available urchins can be a threat to marine plants and alga.

 

[graveyardworm]

Here's an article about urchins, you'll find some info here about their diets. http://reefkeeping.com/issues/2003-11/rs/index.php

Here's an article about seagrasses, I cant find the exact reference regarding seagrass predators, but I'm sure its there and I'm fairly certain uschins are mentioned. http://reefkeeping.com/issues/2006-04/sl/index.php

 

[graveyardworm]

From the seagrass article.

Several families of fishes and invertebrates not only live within the meadows of seagrass but also consume the plants themselves. Urchins, abalones and angelfish have been known to visit seagrass beds for plant buffets. In reef aquaria the popular rabbitfishes, surgeonfishes (excluding the bristletooth tangs such as the Kole and Chevron - Ctenochaetus sp.) and many angelfishes (in particular the larger Caribbean grays and French, Pomacanthus arcuata and P. paru) also occasionally graze on seagrasses. In addition to these fish and invertebrate browsers there are mammalian and reptilian foragers of seagrass. Worldwide, manatees, sea cows and dugongs (Trichechus, Dugong and Hydrodamalis sp.) are known to consume mostly seagrass in their diets. Sea turtles, such as the Caribbean native green (Chelonia mydas) and loggerhead (Caretta caretta), also are prime examples of seagrass consumers in the wild.

 

[Samala]

I've seen Diadema eat small species of grass in captivity when provided for them to sample. I dont know how individual this taste for greens may run though.

>Sarah

 

[piercho]

IME in my tank, Diadema will eat shoal grass, manatee grass, star grass, and turtle grass. I think its safe to say Diadema eats any grass.

Small Diadema sestosum, what usually shows up for sale, tends to stick to the rocks. As it grows and exhausts its prefered food sources, it will begin to cruise the tank and nibble grass. The bigger it gets - and Diadema grows very fast - the more agressively it will graze grass. I've kept a Diadema 2 times and both times the urchin eventually began to graze grass and eventually coral, at which time the urchin got removed. If the grass is well established with a good root system, it will bounce back once the urchin is removed. Newly introduced grass is not likely to survive.

Lately I've been trying a Caribbean rock boring urchin. It is strickly nocturnal and grows much slower in my tank than Diadema did. So far it has avoided plants growing in the sand. Its a thorough grazer like Diadema, grazing rock down to bare "bone", but does not cover much territory. You might try several of these and remove them one at a time as they grow and start cleaning bigger areas. Another issue with these urchins is that they can push very hard with their short spines, pushing off fragments that haven't attached and potentially tumbling rocks.

The other urchin I've tried is the cute little tuxedo urchin. Nice looking urchin, but a real woosey grazer. It would also eat grass if their was some close enough to rock for it to get ahold of.

 

[piercho]

Oh, macro algaes. Diadema eats more macro algaes than any other single grazer I've come across. I'd generally assume that if its a plant, Diadema will eat it. Its easier to give a list of algae that Diadema avoided in my tank:
Asparagosis.
Caulerpa peltata.
Brittle Halimeda, to an extent. It tends to hit just the new growth. Softer Halimedas like H. tuna get grazed.
Sargassum

My Diademas' preferences ran toward crustose algae, especially crustose reds like coralines. Red wire algae and mermaid's fan were other favorites. They would not preferentially graze some noxious algaes like Bryopsis. Some noxious algae, like Asparagopsis, didn't get touched at all. Diadema tends to cruise the tank till it finds a place it likes, where it "digs in" and clears a couple of square inches down to bare rock. Then it moves on untill it finds another spot it likes.

 

[migston]

Will urchins eat bubble algae/Valonia? I've been fighting one of the worst bubble algae outbreaks and need some major help.

 

[piercho]

Valonia that Diadema can get at will get eventually get grazed, IME. Diadema's shape prevents it from getting into close spaces or into the branches of coral.

 

[dalbrecht]

My rock borer goes after valonia as well. They can't get into narrow spaces but if the valonia protrudes they'll go after it.

They prefer coraline tho.