Reproduction Brittle star

1 reproduction

1.1 life span
1.2 regeneration
1.3 fission

reproduction

the sexes separate in species, though few hermaphroditic or protandric. gonads located in disk, , open pouches between arms, called genital bursae. fertilisation external in species, gametes being shed surrounding water through bursal sacs. exception ophiocanopidae, in gonads not open bursae , instead paired in chain along basal arm joints.

many species brood developing larvae in bursae, giving birth live young. few, such amphipholus squamata, viviparous, embryo receiving nourishment mother through wall of bursa. however, species not brood young, , instead have free-swimming larval stage. referred ophiopluteus, these larvae have 4 pairs of rigid arms lined cilia. develop directly adult, without attachment stage found in starfish larvae. number of species exhibiting ophiopluteus larvae fewer directly develop.

in few species, female carries dwarf male, clinging mouth.

life span

brittle stars sexually mature in 2 3 years, become full grown in 3 4 years, , live 5 years. euryalina, such gorgonocephalus, may live longer.

regeneration

an ophiothrix fragilis brittle star missing arm segments póvoa de varzim, portugal

ophiuroids can readily regenerate lost arms or arm segments unless arms lost. ophiuroids use ability escape predators, in way similar lizards deliberately shed distal part of tails confuse pursuers. moreover, amphiuridae can regenerate gut , gonad fragments lost along arms. discarded arms have not been shown have ability regenerate.

fission

some brittle stars, such six-armed members of family ophiactidae, exhibit fissiparity (division though fission), disk splitting in half. regrowth of both lost part of disk , arms occur yields animal 3 large arms , 3 small arms during period of growth.

the west indian brittle star, ophiocomella ophiactoides, undergoes asexual reproduction fission of disk subsequent regeneration of arms. in both summer , winter, large numbers of individuals 3 long arms , 3 short arms can found. other individuals have half disk , 3 arms. study of age range of population indicates little recruitment , fission primary means of reproduction in species.

in species, fission appears start softening of 1 side of disk , initiation of furrow. deepens , widens until extends across disk , animal splits in two. new arms begin grow before fission complete, minimizing time between possible successive divisions. plane of fission varies newly formed individuals have existing arms of different lengths. time period between successive divisions 89 days, theoretically, each brittle star can produce 15 new individuals during course of year.

micro brittle starfish , caulerpa racemosa