Phylum Porifera (sponges) – Lecture 5 Phylum Porifera CLASS
Spicules (needle like structure)
Spongin
CALCAREA
HEXACTINELLIDA
Calcium carbonate
Siliceous Six-rayed
DEMOSPONGIAE HOMOSCLEROMORPHA (found only is 6 ed of textbook ONLY) (∼80%) Siliceous Simple siliceous OR none NOT six rayed th
? Absent
Absent
Present
-sponges are solid because of spongin (fibers that form the skeleton of sponges)
Habitat
Absent, type IV collagen -Integral feature of the basement membrane of epithelium in higher (more sophisticated) animals – some have tissue lvl of organization due to collagen forming a basement membrane under certain structures that are epithelial like
Marine
Marine, deep sea
Marine & freshwater
Marine, inshore
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Exhibit cellular level of organization à only contains cells NO tissue or organs o Multicellular animals o However, recent studies have shown that some exhibit tissue level of organization § Some Homoscleromorpha Share few characteristics with Metazoans (sometimes referred to as Parazans) Sessile aquatic filter feeders o 98% are marine animals (∼5-10 thousand) o Some can “crawl” up to 4mm/day
Cell Types 1. Non-‐tissue nature • 1st animals to exhibit cellular lvl of organization 2. Cellular totipotency • Ability to become any cell type within the animal and do a particular job/function ∗ In particular Archeocyte Shamils
∗ Ex. Stem cells à can differentiate into any type of cell Choanocytes • They are totipotent o When they catch sperm • Ovoid (egg-‐shaped/ light bulb shaped) flagellated cells • They line canal system and chambers o In order to filter feed, have to generate current ∴ need choancytes • Functions: o 1. Generate water current o 2. Capture small food particles § Flagella beats (back and forth) = drags water though collar (exposed end) and microfibrils • As water is dragged any small food particles are captured • Mucous allows the food particle to travel down towards the base of the cell collar à THEN CELL PHAGOCYTOSIS THE FOOD PARTICLE o 3. Capture incoming sperm § Some are Monoeicous à having male and females gonads in the same organism OR Dioecious à male and female organs are found in different organisms Archeocyte • Kings of TOTIPOTENT = can transform into anything o Simpler than choanocytes o Carry nutrition and when they reach a certain portion of the animal they will transform into another cell type and do a particular job/function o They are associated with choanocytes § Receive and digest food particles from choanocytes o No circulatory system o They can differentiate into a bunch of different cells especially cells that are responsible for the secretion of structural features: § Ex: • Sclerocytes à spicules • Spongocytes à sponging • Collenocytes à collagen • Lophocytes à collagen Architecture of Canal Systems à system in which water is dragged from the surrounding environment and the animals picks up particles of food (can be very simple to very complex) 1. Asconid • Simplest organization à there is a functional reason for that • Small, vase/tube shaped (asconoid only in Calcarea) • Red = functional part of choanocytes • Yellow = in most animals it appears like epidermis • Grey = structural matrix of animal à where all the spicules and spongin would be • Have flagellated spongcoels = middle chamber Shamils
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Mesophyl = matrix à where are the spicules is Ostium = incurrent canal à water is dragged from outside the animal into the inside ∗ Many and very small ∗ Porocyte ( tube like) located in each ostium Osculum = excurrent canal à water that is sucked in by ostium is ejected from the animal ∗ One and big Pinacocytes à looks like epithelium but not an epithelium because epithelium requires a basement membrane ∗ Almost like a skin Choanocyte à because they are all close to each other they are referred to as choanoderm ∗ Beat together dragging water through the column (ostium), allows the animal to capture food particles and the direction of current is outwards through the osculum ∗ Not epidermis because its not a true tissue à epidermis is an epithelium tissue, and epithelium tissue is defined by a basement membrane
2. Syconoid • Look like a larger, more complex asconoid • Large and vase/tube shaped (syconoid only in Calcarea) • Red = became a chamber of canals in order to increase the surface area for food capture à tends to be a little bit thicker • Spongocoel NOT flagellated ∗ No choanocytes lining ∴ not flagellated • Instead there are flagellated canals ∴ called flagellated canals lvl of organization
Shamils
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Choanocytes are still beating in unison (together) still dragging water through Prosopyl into the radial canal and out through apopyle à sometime called CHOANOCYTES CHAMBER
3. Leuconoid • The most complx sponges arrangement • More globular shape • Most form large masses (leuconid in all sponge classes) • Red = choanocyte chambers à increase in the surface area available for the choanocytes to generate water current that is dragged through the animal to capture food particles • Have the largest mass due to chambers • Flagellated chamber • NO spongocoel ∗ No big chamber where sea water should be • Usually have more that 1 osculum (excurrent) ∗ Each hole is an osculum à increase SA • Sponge volume = 2.4 cm3 ∗ Osculum # =1 ♦ As the sponge volume increase the # of osculum increase ∗ Dermal ostium # = 940000 ∗ Flagellated chamber # = 29 000 000!