Brittle Star Eggs??????

[DOGMAI]

Ok this is a new one on me. I have had a brittle star for about a year now. It is dark brown with black bands on its legs. It has I would say tripled in size. It is very shy and has never come all the way out of the rocks. If you shine a flashlight on it will just try to hide even deeper in the rocks. Well last night I came home and it was out. It was on the top of the rockwork lying against the back glass. My wife said it had been like that for a while. Well after a while it moved back down into the rocks. I looked at where it had been sitting against the glass and there was a patch of eggs about 2" x 3". I thought they would all be fish food but the fish were leaving them alone. I have another brittle in there but it is a different kind. It is one of the big green ones. Don’t know if they can mate.

Questions:
1. Are they asexual?
2. Has this happened to anybody else?
3. Highly unlikely I know but what would be the mortality rate?

Thanks,
Shane

 

[DOGMAI]

4. Do they even lay eggs or do they give live birth?

 

[klingsa]

Never had that happen before. I don't have any brittles, that I know of, so I'll answer the biology questions and leave the experience ones for someone else!

They lay eggs, and do not give live birth. No animal is completely asexual, and the only asexual reproduction in Echinoderms is fragmentation. Meaning, of course, losing a leg and the leg growing into a new star. No idea about survival rates. I am also surprised that your fish have left the eggs alone.

Good luck, and congrats to the new parents!

Sara

 

[dizzy]

They lay eggs, and do not give live birth. No animal is completely asexual, and the only asexual reproduction in Echinoderms is fragmentation.
Sara

Sara,
I wouldn't be so sure about that if I were you. Exactly which species of brittles stars have been proven to lay eggs.
Mitch

 

[klingsa]

Mitch -
I don't know about individual species, therefore my conclusions are based on Echinoderm biology. According to Biology of the Invertebrates by Jan A. Pechenik,

Many echinoderm species reproduce only sexually, and the sexes are usually separate. All echinoderms except holothurians [sea cucumbers] and crinoids [sea lillies, feather stars, etc.] bear multiple gonads. In the asteroids [including starfish and brittle stars], at least one pair of gonads extends into each arm...In most echinoderm species, gametes are liberated into the surrounding seawater, so fertilization is typically external.

Gametes, of course, lead to fertililzed eggs, then to larval stages. I would not say that they "lay" eggs per se. Eggs and sperm are ejected into the water, and fertilization is external.

Even the most primitive animals, sponges, have sexual reproduction. Every other kingdom, except the fungi and bacteria (no nucleus), also do sexual reproduction. It is entirely possible that the eggs Dogmai found belong to his brittle stars. However, they could belong to something else, and the stars were feeding on them. For a meal like that, I'd come out of hiding too! :lol:

Sara

 

[DOGMAI]

would a clown lay eggs on a vertical surface like that?? What color are clown eggs?? Arent they orange? These eggs were clear looked similar to small bubbles but they were all stuck together. Or could it have been snail eggs? other than that there is not much else in there.

Thanks,
Shane

 

[dizzy]

Sara,
Pick up a copy of "The Modern Coral Reef Aquarium" Volume IV by Fossa and Nilsen sometime. The following quote is from page 321 "It has been shown that Amphipholis squamata in tropical seas reproduces sexually throughout the year. It practices brood care, whereby the maternal animal carries a small number of young in the bursa for three to seven months. Beyond that it is a hermaphrodite, capable of fertilizing itself."

Also under Ophiarachna incrassata Reproduction: Possibly ovoviviparous. There are numberous reports about reproduction in aquariums, however details about spawning or breeding are absent.

I suspect Dogmai might have Ophiolepis superba. From Vol. IV again. Ophiolepis superba
Reproduction: Possibly ovoviviparous, however, details are unknow.

Anyway it's food for thought.
Mitch

 

[dizzy]

Dogmai,
Does your star look anything like this one?

 

[klingsa]

Right, so they do reproduce sexually, the larvae being cared for by the mother, and some are hermaphroditic. That's really not in contradiction to what I was saying, so I believe we are agreeing here. What was it that you were disagreeing about in your first post?

Maternal care has nothing to do with whether or not they are egg layers...the larvae hatch from eggs, whether or not the mother takes care of the brood or not. From what I have learned, I would disagree with the quote from the book saying that hermaphrodites are capable of self fertilization. That is not evolutionarily beneficial, for the same reasons it is not beneficial to humans. The point of sexual reproduction is the combination of different genes. Hermaphrodites, while they have the ability at all times to produce both male and female gametes, do not do so at the same time. Perhaps they will switch within a month's time. Hermaphrodite just means that the animal can produce both within its lifetime.

Shane - yes, clown eggs are orange-red, and can be laid on a vertical surface. Not sure what snail eggs look like, since I've never seen eggs in my aquarium or in nature.

Sara

 

[dizzy]

Sara,
I don't mean to disagree with you. I had O. incrassata spawn back in 1996. I didn't observe the actual spawning and I never saw any eggs. Little red specks just showed up one day. Apparently quite a few people have had O. incrassata spawn and no one has ever reported seeing any eggs. I realize this doesn't prove anything, but I thought maybe we should keep the door open just a little.
Mitch

 

[DOGMAI]

No my star does not look like that. I think that is a serpant star. Mine is similar to the one below but it is a dark dark redish maroon with black bands on the legs about every half inch. The eggs look like little small glass beads. They are all gone now but the star is still acting strange.

 

[dizzy]

Dogmai,
Ophiolepis superba is called the banded brittle star and is different from the so-called serpents stars. Now I'm a little confused on what we call live birth. If the eggs are laid and fertilized outside the body, then picked up by either the male of female, and brooded in either a pouch, bursa, or in the mouth, is it not called live birth when the young are released? For example I hear people say seahorses and bangaii cardinals have live birth. If this is techically not accurate, what would be the correct way to describe it?

 

[dizzy]

Ovoviviparous is defined as producing eggs that are hatched within the body, so that the young are born alive but without placental attachement, as certain reptiles or fishes.

Placenta 1. the organ in most mammals, formed in the lining of the uterus by the union of the of the uterine mucous membrane with the membranes of the fetus, that provides for the nourishment of the fetus and the elimination of its waste products.

Here is my question: Would a fish that is considered ovoviviparous be called a "livebearer" ? If so, does the fertilization of the eggs have to occur inside the fish?

 

[klingsa]

My understanding of "live bearer" is that fertilization is internal, and the young exit the body ready to live physically separated from the mother. That's not to say the parents don't help out, of course. As usual, it's hard to reconcile scientific terms with non scientific terms like live bearer, so I am not sure. It seems to me that ovoviparous animals, such as mouth brooders among fish, are no different than a chicken which incubates and protects its eggs before they hatch. Internal fertilization, external incubation, but we still say they are egg layers. If the definition of ovoviparous purposely excludes placental attachment, then it may be fair to assume that live birth necessarily includes placental attachment. However, the majority of animals which do have a placenta are mammals, as you pointed out, and I can't say for sure that no non-mammals are considered live bearers. I would assume that it is like most things in biology...there are exceptions to everything!

Sara

 

[Anonymous]

Mitch wrote:

Ovoviviparous is defined as producing eggs that are hatched within the body, so that the young are born alive but without placental attachement, as certain reptiles or fishes.
Placenta 1. the organ in most mammals, formed in the lining of the uterus by the union of the of the uterine mucous membrane with the membranes of the fetus, that provides for the nourishment of the fetus and the elimination of its waste products.
Here is my question: Would a fish that is considered ovoviviparous be called a "livebearer" ? If so, does the fertilization of the eggs have to occur inside the fish?

Short answer, yes and I don't think it matters. An ovoviviparous example would be seahorses. I'm not sure where the fertilization of seahorse eggs takes place. Both viviparous and oviviparous fish give birth to live young. In oviviparous fish, the young are nourished by yolk sacs. In viviparous fish, the young are nourished by the mother.


Sara wrote:

Maternal care has nothing to do with whether or not they are egg layers...the larvae hatch from eggs, whether or not the mother takes care of the brood or not. From what I have learned, I would disagree with the quote from the book saying that hermaphrodites are capable of self fertilization. That is not evolutionarily beneficial, for the same reasons it is not beneficial to humans. The point of sexual reproduction is the combination of different genes. Hermaphrodites, while they have the ability at all times to produce both male and female gametes, do not do so at the same time. Perhaps they will switch within a month's time. Hermaphrodite just means that the animal can produce both within its lifetime.

It is when an organism can't find a mate. Lots of flowering plants do it for the same reason. There's even a species of lizard that reproduces through parthenogenesis--the female gives birth to exact clones of herself without any male fertilization.

Now then.

Echinoderms reproduce by shedding their eggs and sperm into the sea, where fertilization takes place....They float in the currents before settling and metamorphosing into an adult.

From The Manual of Marine Invertebrates, Haywood and Wells.

I suspect those eggs may have been laid by a snail. Do you have any hitchhikers you've noticed?

 

[DOGMAI]

When I say they give live birth I mean like a human or a guppy the babies come out alive. They do not come out as eggs that still have to hatch.

I have four different types of snails in my tank.

Bumble bee
Nassarius (the newest in my reef)
A black burrowing snail (cant find a pic)
A white snail that looks like a Mexican turbo but it is white with brown bands.

As far as anything new, I have not seen anything.

Thanks,
Shane

 

[Anonymous]

I would bet the farm those are snail eggs.

 

[klingsa]

Matt wrote:

It is when an organism can't find a mate. Lots of flowering plants do it for the same reason. There's even a species of lizard that reproduces through parthenogenesis--the female gives birth to exact clones of herself without any male fertilization.

True, Matt, good point. Mendel found that out with his peas! I should have said, it is not their first choice. Parthenogenesis is asexual reproduction, so that's not self fertilization, or any kind of fertilization at all. That's pretty amazing for a lizard, though. Cnemidophorus exsangius is one of them.
I still don't see, however, how it is evolutionarily beneficial for an animal to be only parthenogenic, as this lizard is, as well as some rotifers! Oh well, I guess it works for them.

Sara

 

[SnoopDog]

Well my 29 gallon has had baby stars for a year now in the macro algea, some are getting quite large. There has always been two adult brittles in there and no more. Here is the one of the adult brittle when we found he was inhabiting the Aqua-c (wondered where he went)

Ok now here is what the babies look like that are popping up everywhere not a great shot.

I thought maybe they could be a smaller species that do not get large, well i was wrong because here is one that grew up in less that a year.

I trimmed my macro algea for a friend last week, he took home about 8 baby stars because we could see them through the bag. I got to see about 20-30 larger baby stars around and inch in diameter during this trimming. I am guessing they like the algea because that is where i find them hiding out. Can any one i.d. the last picture ? And yes i know the babies are not the same species of star, i cant understand where they are coming from.

 

[Anonymous]

Parthenogenesis is asexual reproduction, so that's not self fertilization, or any kind of fertilization at all

I'm glad you caught that....makin' sure you weren't asleep.

I'm not really sure what the theory is on the existence of parthenogenesis as a sole reproductive mode. Maybe I'll ask one of the Evolution profs on campus. Keep in mind it only exists in a miniscule percentage of the millions of species, so it isn't a very successful mode.

Snoop, I'd guess they just hitchhiked in on your LR and have grown up in your tank.