Question

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1 Man y animals that undergo metamorphosis switch from a sedentary lifestyle to one in which they are highly mobile, and able to undergo geographic dispersal; others are able to disperse as larvae, and then metamorphose into a sedentary adult. Describe the pre- and post-metamorphosis dispersal capabilities of: Abalone Barnacles Butterflies Sea Urchins

Answer 1

Abalone-> Abalone larve known as trochophore, which hetched from fertilised egg after 24 to 48 hrs of fertilisation (denpends on temperature). Trochophore can move in water using flagella type structure. Next stage is veliger, in this stage it remain for 3 days and ultimately settle down on rocks or bottom, it can also move or glide in water using flagella and suquid like structure. after settlement post larvel dispersal includes gliding and bumping.

Barnacles-> Napulis is the first larve of Barnacles, Napulis has ability to swim freely like zooplanktons. Napulis molted into cypris, which finds a suitable place to attached, acording to the waves and tides it decides a surface to cement on. first it used its head to attach then it secrects some biological glues. So Napulis and cypris involves in dispersal.

Butterflies-> caterpiller is first larval stage, have very small legs like structures and fragmented body for movement, they move by contraction of body and using legs. its main work is eating, when it done with eating it changes into pupa, pupa doesnot move it remains stationary, but a lot of metamorphologica changes occurs in pupa. it is pupa which is give birth to butterflies. Adult of butterflies have wings, so main role in dispersal is of adult.

Sea Urchins->  echinopluteus is swinging larva of Sea Urchins. Echinopluteus migrate into the upper surface waters and have long ciliated arms which are also used for feeding. Their arms are supported by slender calcite rods. After a few weeks of living and feeding in the plankton it started molting into adult. As the rudiment develops, adult features, such as tube-feet, begin to appear, while larval structures, including the arms and even the larval gut and mouth, are resorbed and eventually lost. The newly metamorphosed juvenile sinks to the sea floor to begin life as a benthic adult.