sessile

Examples of sessile in the following topics:

• Phylum Cnidaria

  • Polyp forms are sessile as adults, with a single opening to the digestive system (the mouth) facing up with tentacles surrounding it.
  • The sessile polyp form has, in fact, two types of polyps .
  • The anthozoans, the sea anemones and corals, are all sessile species, whereas the scyphozoans (jellyfish) and cubozoans (box jellies) are swimming forms.
  • The hydrozoans contain sessile forms and swimming colonial forms like the Portuguese Man O' War.
  • The sessile form of Obelia geniculate has two types of polyps: gastrozooids, which are adapted for capturing prey, and gonozooids, which bud to produce medusae asexually.

• Planctomycetes

  • The life cycle of many planctomycetes involves alternation between sessile cells and flagellated swarmer cells.
  • The sessile cells bud to form the flagellated swarmer cells which swim for a while before settling down to attach and begin reproduction.

• Polyps in the Colon

  • If no stalk is present, it is said to be sessile.
  • Polyps that are pedunculated (with a stalk) are usually less dangerous than sessile polyps (flat polyps).
  • Sessile polyps have a shorter pathway for migration of invasive cells from the tumor into submucosal and more distant structures, and they are also more difficult to remove and to ascertain.
  • Sessile polyps larger than 2 cm usually contain villous features, have a higher malignant potential, and tend to reoccur following colonoscopic polypectomy.

• Physiological Processes in Sponges

  • Sponges are sessile, feed by phagocytosis, and reproduce sexually and asexually; all major functions are regulated by water flow diffusion.
  • Since gemmules can withstand harsh environments, are resistant to desiccation, and remain dormant for long periods, they are an excellent means of colonization for a sessile organism.
  • Sponges are generally sessile as adults and spend their lives attached to a fixed substratum.

• Pre-Cambrian Animal Life

  • The earliest life comprising Ediacaran biota was long believed to include only tiny, sessile, soft-bodied sea creatures.

• Leaf Structure and Arrangment

  • Leaves that do not have a petiole and are directly attached to the plant stem are called sessile leaves.

• Phylum Porifera

  • Sponges lack true tissues, have no body symmetry, and are sessile; types are classified based on presence and composition of spicules.

• Class Anthozoa

  • The larva settles on a suitable substratum and develops into a sessile polyp.

• Chordates and the Evolution of Vertebrates

  • Most tunicates live a sessile existence on the ocean floor and are suspension feeders.

• External and Internal Fertilization

  • For sessile aquatic organisms such as sponges, broadcast spawning is the only mechanism for fertilization and colonization of new environments.