What Is The Advantage For A Sessile Animal To Produce Free Swimming Larva?

Sessile Definition

Biologically speaking, an organism that is sessile (equally opposed to motile) lacks the ability of cocky-locomotion and is predominantly immobile.

In zoology, sessility applies to those animals which are attached to a substrate. Most often these are marine animals, such as mussels, although parasites such every bit the cochineal insect assume a fixed life bike upon their plant hosts.

Sessile organisms do good from lower energy expenditure than motile creatures and can thus subsist on relatively low amounts of nutrient, every bit they have a low metabolic rate. Nonetheless, sessile organisms need to catch their nutrient and respond to stimuli from any bending. For this reason, they often display radial symmetry as a body plan.

Typically, sessile organisms can move past using culling methods such as water currents or current of air and they often accept a motile phase in their life wheel. Some marine animals, such every bit jellyfish, have a sessile larval stage equally a polyp, leading to a motile stage as they reach maturity. Conversely, organisms such as barnacles accept a motile, pelagic larval stage and become sessile in their adult life.

Barnacles

The image above shows barnacles, which accept a motile larval stage and a sessile adult phase.

Sessile organisms may grow on a substrate such as a rock or tree trunk, or, in organisms such every bit corals, they may lay downwardly their ain surface from which to grow; the substrate created by corals makes upward the solid construction of coral reefs.

Many sessile organisms display 'clumping' beliefs, in which the individuals group or abound shut to 1 another. This is beneficial because reproduction is made easier due to the close proximity of mates, as well as providing better protection from predators. Alternatively, organisms may protect themselves chemically, through the use of toxic thorns or cnidocytes.

In botany, sessility applies to plants which are characterized by a lack of petiole (the stalk which attaches the foliage to the stem). In this instance, the flowers or the leaves grow directly from the stem or peduncle.

Trillium cernuum

The prototype above shows Trillium cernuum. This plant has sessile leaves, which abound directly from the stalk.

Similarly, in anatomy, a sessile structure such every bit a cyst or a polyp lacks a stalk or peduncle.

Motile – Referring to the ability of organisms which are capable of contained locomotion.
Inflorescence – The arrangement of the flowering head of a plant.

Quiz

one. For a barnacle, a benefit of sessility is:
A. Lower requirement for nutritional intake
B. Sessile organisms are less vulnerable to predators than motile organisms
C. Sessile organisms accept amend access to nutrient

Answer to Question #1

A is correct. Considering sessile organisms do not need to expend energy on movement, they do not demand to learn as much diet as motile organisms.

2. Sessility in plants refers to:
A. Plants which do not plough toward the sun
B. Plants without a stalk attaching the leaves or flowers to the stem
C. Plants that non have a stem

Answer to Question #2

B is right. In botany, a plant that is sessile has leaves or flowers which branch directly off the main stem of the found.

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