Thaliaceans have complex lifecycles. Doliolid eggs hatch into swimming tadpole larvae, which are the common larval stage for other urochordates. Pyrosomes are ovoviviparous, the eggs develop inside the "mother" without the tadpole stage. Salps are viviparous, the embryos are linked to the "mother" by a placenta. This then develops into an oozoid, which reproduces asexually by budding to produce a number of blastozoids, which form long chains (see image). The individual blastozoids then reproduce sexually to produce the eggs and the next generation of oozoids.