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FAQs about Sea Star Reproduction

Related Articles: Sea Stars, Brittle Stars, Asterina Stars, An Introduction to the Echinoderms:  The Sea Stars, Sea Urchins, Sea Cucumbers and More... By James W. Fatherree, M.Sc.

Related FAQs: CC Star Reproduction, Linckia Reproduction, Sandsifting Star Reproduction, & Sea Stars, Sea Stars 2, Sea Stars 3, Sea Stars 4, Sea Stars 5, Brittle Stars, Seastar ID 1, Seastar Selection, Seastar Compatibility, Seastar Systems, Seastar Behavior, Seastar Feeding, Seastar Reproduction, Seastar DiseaseAsterina Stars, Chocolate Chip Stars, Crown of Thorns Stars, Fromia Stars, Linckia Stars, Linckia Stars 2, Sand-Sifting Stars,

sea star regeneration 8/18/08 My daughter is doing a science project on the regeneration of arms of Seastars. We have a lot of Seastars from the Great South Bay of Long Island. She wants to see if the rate of regeneration has anything to do with the size of the Seastar. Also, there are several very small Seastars. What do they eat? <Mmm, need to know the species involved to be sure... use your search tool/s re... with the words Seastar identification (and the general geographical) location> Can they open up a mussel or clam? <Maybe small ones, but... can likely be fed a prep./mix of meaty seafood you can make buying, cutting up, freezing a bag of "mixed frozen seafood", offering small bits of this every few days> Is there a safe way to tag or mark the Seastars so she can identify them? <Mmm, don't know... can/do remove everything from their surfaces... I would use a digital camera, flash to identify individuals from the markings near their madreporites> Thanks for any help you can give. Cindy <Welcome. Bob Fenner>

Sea Star Regeneration? – 03/10/08 Hello, <Hi Ross.> Back in September, Marco responded to a question I had about my cold, salt water tank. Since I'm not sure who will be responding, I'll give a quick overview before my question. <You got me again. I remember your case.> I have a 100 gal., cold (68?F) salt water tank. It currently only has invertebrates from the New England area (Boston, to be more specific). I was having trouble with my Nitrates and have since been adding sand to create a DSB. <In your pictures it does not look very deep, but I may be wrong. How deep is it?> My Nitrate problem is still there, but it fluctuates... <How high and how are the fluctuations? Do you still use bioballs? Do you use absorbing resins? How much water do you change regularly?> but that is not the reason for my question today...or perhaps contributes to it. (Nitrites and Ammonia are 0ppm) Recently, one of my larger sea stars (I believe it is an Asterias forbesi) started acting strangely. The central disk looked like it became soft. <That’s bad. Sorry to hear.> Then one day there was an arm on the ground. A few days later, the central disk was completely gone <An important information.> and 4 arms were left. I've attached two pictures of one of the arms. In one, the arm is crawling away. In the other, it is on it's side and you can see the tube feet. Now my questions: 1. If this is some form of asexual reproduction, I can't say it was very successful. <No, not if the central disk dissolved. For asexual reproduction the arms keep a part of he central disk. In addition, they rather form two halves, not five.> Even though the arms survived for a day or two, they ultimately were preyed upon by my hermit crabs and sea urchins. I had to remove them from the tank. 2. Even if the arms had survived, how could they? <They can’t without a part of the central disk, which will form new organs pretty fast and in part prior to the division.> When the arm is regenerating, how does it eat, get oxygen...even move (there is no madreporite to bring water into the water vascular system). <Exactly the reason why a part of the central disk has to be attached for successful regeneration. If not, it’s up to osmosis, maybe diffusion and using what is left as good as possible. With the nervous system acting independently the arms of your stars survived a few days, amazingly more than mine would if separated.> Everything I've read just says "sea stars have amazing powers of regeneration" <Only under good environmental conditions and with proper nutrition. In aquaria many don’t survive very long.> but don't explain how they survive during this period...or even how long it takes. <A new disk and tiny arms form pretty fast, within a few weeks. The part of the central disk connected to the arm will do the supply with a little madreporite (and other organs) that divided itself. It can take a few years (!) until the sea star has long arms again.> 3. If the fragmentation wasn't for reproductive purposes, what do you think it was? <Many possibilities, temperature too high for too long, insufficient water quality, wrong nutrition are options, you may know what is most likely… by the way did you measure nitrates prior to its death or afterwards. Such a dead sea star can significantly contribute to the organic load.> I was really bummed that one of the arms didn't survive because I thought it would be cool to document the regeneration process. Any thoughts on what happened to my poor sea star would be appreciated. Thanks. –Ross <I hope this helps. Also have a look at http://www.wetwebmedia.com/starreprofaqs.htm and http://www.wetwebmedia.com/stardisfaqs.htm and the further FAQs on disease (see how many people loose their Seastars?). Cheers, Marco.>

Re: Sea Star Regeneration? Nitrates; positive feedback 03/12/08 4/7/08 Hi Marco, <Hello Ross.> I wanted to give you an update on my tank. So far, good news <Nice to hear.> (better knock on some wood, I guess). I don't know if you recall, but I inherited the tank from some students, I didn't set it up myself. After your last email, I did a close examination of everything. It turns out the air pump to the protein skimmer was very weak. I replaced it with a much stronger pump and the efficiency of my protein skimmer has improved dramatically. <Very good.> I removed some bio balls and got a Nitratelock resin bag. <I’m not a fan of the latter, but certainly an efficient short term solution.> The tank has never been cleaner. The nitrates were 160+ but this morning they were 20ppm. <That’s much better.> I did lose another small sea star close after one of my others broke itself apart, but I have a large one left who seems healthy. Part of my urgency in lowering the nitrates etc. was that I knew a student was going to be getting a cuttlefish for a research project and the tank needed to be healthy. We've had him (her?) <Males often become aggressive towards their reflection in a mirror, but that's not 100% reliable at all.> now for almost two weeks and things seem great. (again, knock on some of that wood). Thanks so much for your help and suggestions. –Ross <Thank you very much for the feedback. It’s very good to know what happens after the emails. Good luck with your cuttlefish. Marco.>

Mating Starfish?  3/10/07 Hi, <Brian> I have two sand-sifting starfish in my tank.  They are almost always on top of each other (see attached photo). <I see> I can't find anything on the site about this?  Are they mating? <Likely so, at least trying, yes> Both seem to be fine.  They've been in the tank for about a month, and whenever they aren't joined up, which is rare (at least during the day when I can observe them), they move about fine.  Any ideas what they're up to? Thanks, Brian <Mmm... perhaps a trip to a large/college library that has a life science, organismal biology arm (e.g. Zoology)... for a helping hand at searching the literature (reference librarian)... re Archaster reproduction... I do think this species is a "typical" Asteroid (not a brooder, but a broadcaster) of fertilized eggs... pelagic larval stages... much that you can't provide in a captive setting as a mixed hobbyist aquarium... Do take a read here: http://www.wetwebmedia.com/starreprofaqs.htm Bob Fenner>

Starfish Reproduced? Not this time  - 08/15/06 Hey guys, Quick question for you. I have two green Bahama starfish in my 90gal tank. Tonight, it looked like one of the starfish everted its stomach, but after about 10 minutes, I looked back and it left a whole section of what I thought was its stomach on the glass and it moved on. The 'gunk' was sticking to the glass with some tube feet, so I thought it may have eaten one of my sandsifting starfish and it disagreed with him, but upon closer examination, the 'gunk' started to unravel and move about. I'm guessing it just reproduced, but right now it looks like a cucumber. I'm attaching pictures, so if you could confirm what I'm seeing, I'd appreciate it. Hope the pics are not too large. First  pic is the starfish. Second pic is what it 'released' <Does appear to be an actual sea cucumber... might have been ingested... and egested (for sure!)... not palatable. Thanks for sending this account, pix along. Bob Fenner>

Re: Starfish Reproduced?  - 08/15/06 Bob, Thank you for the quick reply. I do have one concern though. I did not have any sea cucumbers in my tank to start with. I avoided purchasing them for the potential of poisoning a tank upon stress/death. <Likely a "recruit"... most likely came in as part of live rock... perhaps live sand, or other hard substrate with other livestock> I'll keep researching I guess. It has very similar skin to the green Bahama starfish with greenish color and small spikes on the body. I don't have enough knowledge about reproduction, <Can be found in textbooks, the Net... looks to me to be a Holothuroid though...> so I can't say that is what happened though. If you'd like me to send you occasional updates, let me know. <Thank you, please do. Bob Fenner>

"Baby Starfish" 7/12/06 Hello WWM Crew, I am a Marine Hobbyist. I have a 75 gallon reef tank. Learning things all the time. Loving it. Tried to search the web on this new issue, but can't find my answer. Did find you, and I'm hoping you have the answer. I'll only mention in this e-mail what I think is relevant to keep this short for you. I have a relatively big (hopefully fully grown) gray (with stripes) serpent starfish, and also an orange starfish (don't know the species off hand--slow moving, smaller). Anyway, this evening I saw a tiny baby starfish in the tank. It moved fast like the serpent. Looked like somebody had tried to take a bite out of a couple legs.   It didn't have any color though--just white. I was trying to figure out how the starfish reproduce. Everything I found on reproduction talked about splitting, which didn't happen here. Is it possible my single starfish laid eggs and fertilized itself? They don't cross breed, right? And are they "born" white and color up as they age? And while I'm writing. <No mystery here!  The tiny brittle stars are a separate species and were probably introduced with live rock or corals.  They often reproduce prolifically in reef tanks.  The reproduce by splitting and by direct development (brooding) of young.  The are a joyful and beneficial addition!> I lost my very large (7 or 8 inches) Mr. Goby. And then I lost my cleaner shrimp. My daughter thinks the serpent star ate them. Although the coral banded shrimp may have taken the latter. Do you think that is possible that the serpent star ate my fishes? <It is possible, but not likely.  Generally, smooth armed (serpent) starfish are considered safe while spiky armed (brittle) starfish, especially the green ones are considered at least risky to small fish and inverts.> I have not been feeding him frozen fish because I was afraid of how much bigger he could get, but maybe I should feed him frozen to keep him from eating everything else. What do you think about that? Thanks in advance for your wisdom. Vickie <As these animals get larger, it gets harder for them to get enough food.  Feeding it small bits of food will not only help prevent it from resorting to predation, but will more simply save it from starving. If it eventually outgrows your system, you can either trade it or use it as an excuse to get a bigger tank! Best Regards, AdamC.>

Starfish Regeneration (5/9/05) Hello Bob.  <Steve Allen covering Echinoderms tonight.> I know that starfish are great at regeneration and can become whole animals from being cut apart but I never thought I would watch one split itself in half! These are the starfish that came with the live rock and I have no idea what kind they are.  <Are we talking about the tiny ones that never get bigger than a penny? These are genus Asterina. They often have an unusual number of limbs or irregular limb length. The often reproduce by fission.>  I thought it was dead until I saw the two parts move away from each other.  No, flying will probably never get better for me as a work related accident, shortly after high school, did some damage to my back, neck and knee.  <Sorry to hear. As one who flies 12,000 miles per month, I'm sure flying is even more uncomfortable with the lingering effects of injury.> Now that we are getting to know how to use the camera we will take some pictures of the tank. I should have some good stuff over the weekend.  <Cool. Do consider joining our chat forum and posting them there for all to enjoy.>  I hope you have a great weekend.  <I don't know about Bob, but I sure did--I got to be home.>  

Sexual Dimorphism of Chocolate Chip Stars (11/17/04) Difference in male and female chocolate chip sea stars. <I am not aware of any visible external differences between the two. Steve Allen.>

Archaster Babies?....Or Asterina? (11/1/04) Believe it or not, MORE Archaster craziness! Anthony, you are a patient man for answering all my questions. Bless you indeed! :) <I will pass this on. Steve Allen responding since Anthony is out.> To add to the insanity, one of the Archaster's had BABIES. I've got a few, literally, the size of an eraser head. I tried to take a picture, but it was incredibly difficult as it was far back in the tank, glass distortion, very small, etc. So everything around it looks HUGE. Here's the pic: I'm not really sure how many I have as only two were visible, now only one. Hopefully some of these guys will survive and won't suffer from predators so I can pass them on. :) <Looked at the picture. Sorry to rain on the parade, but I doubt that this is a baby Archaster. Looks more like an Asterina to me. These common hitchhiker mini stars seldom exceed 1 cm in diameter. Look at some pix on our site and elsewhere to compare and be more certain.>

Starfish Asexual reproduction My sand sifting starfish recently looked like it was in a molting stage. Its legs were deteriorating off and she was still alive so I was giving her a chance to prove herself worthy of staying in my tank.  Guess what, she disappeared and now I have over 50 baby starfish in my tank. <Are you sure its the same kind of starfish? Often there are little tiny star that appear in fish tanks that can become nuisances.> I’ve never had a daddy in the tank.  And I’ve had this starfish for about 6 months.  Do you know what the reproduction cycle is as to maybe she was pregnant when we received her or did she a-sexually repro in my tank. <Sounds like asexual if they are indeed from her. A picture of some of the babies would help.> My 55 gallon tank won’t support this many stars, so if any one wants to make a purchase, just contact me. <Sorry we can't help you with the selling part but I'm sure if you want to post them on some of the multiple web sites you'll have much success> A Star Is Born...Well- Several Stars! Hi, <Hi there! Scott F. here today!> My name is Nanci and I have 2 sand sifting star fish which have successfully reproduced.  I saw the first babies about 1 1/2 weeks ago. <Very cool!> I have no idea how many are in the tank, due to the fact they are so small (1/8” – ?” in diameter) and are the same color as the sand. They seem to be at various stages of growth.  Some are still oval in shape while others have already started growing their arms.  Does this indicate they have reproduced more than once or just different growth rates? <Hard to say. Probably different growth rates in different individuals...> The “parents” are about 4”-5” in diameter.  What is the time line for growth? <Growth rates vary by species, but I imagine that you'd be looking at several months at the least.> Do I need to add anything to my tank to help these little ones survive?  Should I move them to another tank, and if so, at what stage?   <I'd leave everything as is- and I'd let them remain in the same tank> My 55 gallon tank is pretty self sufficient at this time, it’s only been running for about 9 months.  I have 1 Kauderni Cardinalfish, 1 White-Tailed Damsel, 1 Orange-Spotted Watchman goby, 1 Kole Tang, 1 Ocellaris Clown, 1 Fridmani Pseudochromis, 1 Blue Damsel, 1 Condylactis anemone (nuisance, but cool), Finger Leather, Button Polyps, Xenias, Yellow Polyps, Green Polyps, hermit crabs, Turbo snails, Bumblebee Snails and 1 Blood Red Fire Shrimp.  Will any of these harm the babies?  Will the babies harm any of these? <Depending upon the species that you have, there will probably be little danger to the corals. If the adults are leaving 'em alone- chances are that the babies will, too!> The babies do climb the live rock, unlike the parents.  Any and all advice would be helpful. I haven’t been able to find any info on the net. Thanks a lot and have a great night! Nanci <Nancy- if we could get a good picture, we could make a reasonable attempt at an ID, and give you some more definitive answers. Best of luck with your little stars! Regards, Scott F>  

Mating Stars? (7/28/04) Hi there: <Hi. Steve Allen here.> I took this picture a few min.s ago (photo attached), these two have been this way for about two days now. Just wondering if they are indeed mating, and if there are any precautions we need to take to keep the little ones safe. <Could be, but hard to be certain. Echinoderms spawn into the water. No copulation involved. If they do reproduce, there is nothing you can do in a reef tank setting to protect the eggs or baby starfish. It is almost impossible for them to survive and grow to adulthood in there. Too many other things available to eat them. That's why they produce millions eggs in the wild--only a few survive. In the confines of a tank, they are even less likely to survive.> We have shrimp, crabs, snails, a yellow tang, two clown fish and a fish that looks like Dory from Finding Nemo. <Paracanthurus hepatus> It’s my husband’s tank, so I don’t know all the fishes proper names :-) Thanks for any help or tips you might have and feel free to use the picture if you’d like. <Nice picture. Hard to say what they're really doing. As far as actually breeding starfish, you might want to do some searching on the internet for info if anyone is doing this successfully.> Thanks, Lecia Zinna

Starfish Couple? (3/17/04) Bob, <Steve Allen tonight>   I have a pair of sand sifting starfish that I purchased from the same tank. After I first introduced them to my tank they did a great job sifting around. Now they have found each other and the one just lays on top of the other and they don't seem to do much but lay in one spot all day. They are both still alive. Are they breeding? <Hard to say. Starfish are known to be rather still at times. You could always separate them & see how they react. If your water is good, there is food available, and they don't show any signs of decay, they're probably fine. Thanks, Rob <Hope this helps.>

Attack of the Star People! >Hey everybody!   >>Hey you! >Hope your holiday was fun.  I have a question about my starfish, he is gray with burgundy spots and blue tips at the end of his arms.   >>Sounds purty. >It seems that someone bit off one of his arms and the arm is on the live rock. >>Mm.. kinda like that one old movie with Michael Caine, "The Hand", yeah?  (The one where he's driving with his hand hanging out the window and a truck comes along too close and kinda.. whacks it off?  I was pretty little when I saw it..) >My question is, have you ever seen an arm survive on its own? >>Only in the movies.. Oh wait!  You mean a starfish arm, doncha?  Yeah, sure have.  Needs to have just a bit of the central disk and yeah, it'll regenerate.  Pretty strong weirdness vibe thing going on there. >It appears to be getting longer and not changing colors as if it were dead!   >>Oh yeah, you've got a star-ltergeist. >I've left it there to see what would happen. >>Watch out if it starts throwing things and moving furniture.  You may need an exorcist. >I really thought that someone would come along and eat it, but it seems to be growing.  Any clues what's going on?   >>Yeah, funky nature in action! >Weird science!   >>Big time. >Thanks, Valerie >>Welcome, Marina

Urgent!!! Starfish Spawning To Bob Fenner, and other great WWM team, Just few hours ago, I bought two Protoreastor nodosus to my aquarium (my aquarium is  so small, only 60 x 30 x 36) and surprised when I see the transport bag fulfilled with milky solution with two big stars in it. So, I just thought it's only former water quality, but I remembered the former was as normal as yours. So, I move the stars to my aquarium, and I noticed one of them having a typical body secretion between arm's joint. It seems to be a sperm batch, and now it clouds my aquarium. He was still emits the unpleasant concoction to the water, and I only hopes the filter can eliminates every sperm cell. And other starfishes like my four Archasters, two Fromias, and six Sabellastartid worms are unknown in condition. But, three of the four Archasters looked very nervous and stressed when the new "housemates" come. Very unusual, they climbs the aquarium wall and moving with a fast coordinated motion. And their skin was exuding slime, a clue for invertebrate's stressed condition. Did the aquarium should to be cleaned or it will cleaned itself? Did the sperm will poisoned and toxified other inhabitants? Did they will eat other starfishes too? And how to stop this? Thank you very much, Anargha. <I would keep a close eye on your water quality (testing for nitrogenous wastes at least daily for a while). If the other livestock appear to be stressed, I would initiate a considerable water change (25%) and have more pre-made water on hand for further changes. No way I know to "stop it"... conditions are likely "so good" in your system that spawnings are induced. Bob Fenner>

- What Are They Doing? - hey gurus- <Hello to you, JasonC here...> i have 2 sand sifting stars. one has been draped on top of the other for about 24 hrs. now. the one on the bottom has moved around the tank, so i know he's not dead. is this a mating ritual or what? thanks Justin <Perhaps, but hard to say for certain. Cheers, J -- >

Re: question on starfish Hello again i read up on breeding starfish and wondered if my sand sifting star splits or lays eggs? <Can actually do both. Split asexually and produce either eggs or sperm> i have one that loves my tank thanks JM. Also could you direct me two the decorator crab facts on your page I've typed it in google and nothing has came up? thanks again JM <Sure. Please see here: http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm and the Related FAQs (linked in blue at top). Bob Fenner>

Starfish breeding Hey Bob: I have been wanting to breed starfish. I was able to do this once before with a red Fromias but due to a lack of proper maintenance (lazy me) had a nitrate blow up and lost them all saved everything else though. I know you do not recommend blue Linckias but how about the purple Linckias?  <Gorgeous creatures... Tamaria stria... just look something like the genus Linckia... can be quite hardy in fully established reef systems of size> Or should I just go back to the cheaper Fromias? I would like to raise the starfish that would be more popular but also way more hardier. <Go with the Fromias> Needs to be soft coral safe, I do so like my xenias and leathers. And would you recommend foods? <Hmm, yes... a little joke here. Tablets likely... as are easy, nutritious, sink...> Also do not much care for the brittle and serpent stars. <Not appropriate technology in many cases, settings> And what about the crabs? Should they all come out? I have 1 sally lightfoot, several left handed hermits, and a unidentified stowaway (kinda looks like a shamefaced, I'll send pics once it is caught). Please advice and once again thanks for all the help. <Would keep eye on any, all crabs...> If not for your advice I would have already scratched this hobby and went back to the old tinker-toys and play-dough. <Ahh, glad to have helped... and glad you're "still with us". Bob Fenner> Kevin Johnson

Sand Sifting Star Wow, you're quite a versatile person. When I first started keeping a shark I contacted you, and thank you for your response. It so happens that I have a couple of sand sifting stars, Archaster typicus in my tank right now, and they seem to be doing what pseudocopulating starfish do when you have a male and a female (who knew??!!). Anyway, according to what I've read so far, she's going to dump about 2 million eggs into my 125 gallon aquarium, and he'll successfully fertilize, I don't six of them. Anyway, I have pretty good circulation and filtration on the tank, including UV filtration. I am also, apparently, host to some bristle worms (remind me to get a trap). I have a medium sized cat shark, and three four very brave and smart damsels, a very large cowry, some turbo snails and about 4 blue legged small hermit crabs. So, am I going to have baby starfish in two months? <Not likely... Seastars reproduce asexually in captivity at times... and there are brooding types that produce young in aquariums, but the sexual type... requires long enough planktonic stages, feeding... that the filtration, other life in a contained space take all out> Should I break out the cigars? Or, am I just going to have to cut down on the brine shrimp for a while because the damsels will eat them all?? There is literally zero information on the Internet about breeding starfish in captivity. Can it happen? If so, what can I do to improve success? If I have 2 million of them at $11 a piece I could retire. I now know more about Archaster typicus than I ever wanted to know, including the placement of all its major organs. I know what the larvae looks like in all of its stages, but am I the first to see the miracle of life happen in my home aquarium? Is my tank that dirty? :-) Thanks, Ted Coombs

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