Porifera

Class Hexactinellida

- 6-rayed, pointed silica (SiO2) spicules (live in deep cold parts of ocean) - Tube shaped - glass sponges, have spicules composed of silica that join together to form a 3D netlike skeleton - Common name: Glass Sponges

Class Calcerea

- Calcareous sponges with spicules composed of Calcium carbonate (CaCO3) --> will dissolve if acid is added - often have rough texture with the spicules extending through the outer covering of the sponge - small-sized, often live in warm, shallow environments - Common name: scypha

Skeleton is made of what?

- Collagen - Spongin and Spicules - Calcium carbonate or silica

Syconoid

- Flagellated canals, have gemmules - intermediate body structure of sponge that has incurrent canals, and choanocyte chambers that increase the surface area (to ensure all cells get nutrients) in which choanocytes are located - openings called dermal pores (on multicellular epidermis) that are lined by multiple cells, no porocytes - water flows through dermal pore, into incurrent canal, into spongocoel, into choanocyte chamber, and is then pushed through osculum - body type for some calcerea and hexactinellida

leuconoid

- Flagellated chambers - most complex body type (adult sponges): all large sponges, no central cavity, have narrow canals, endo- and exo-pinacocytes, mesohyl, many small interconnected chambers. no porocytes - choanocytes only located in choanocyte chambers - has excurrent and incurrent canals - water flows through dermal pore, to incurrent canals, to spongocoel, into choanocyte chambers, to excurrent canals, and then out through the osculum - body type for all 3: calcarea, hexactinellida and demospongiae

Asconoid

- Flagellated spongocoels - simplest body pattern for sponges; stalk-like spongocoel covered with a single layer of choanocytes. - Structural category of porifera- typically small sponges, layers of pinacocytes called pinacoderm that is 1 layer thick. - water from outside flows in through ostium, and is pushed through osculum by choanocytes lining the spongocoel - body type for some calcerea sponges

Asexual reproduction of sponges

- Fragmentation (a chunk comes off and becomes a new sponge) - Budding (a part of the parent organism pinches off and forms a new organism) - Gemmule formation - Regeneration

How sponges avoid predation

- Hardened structure - toxins - foul taste to predators

Feeding mechanisms

- Heterotrophic Filter feeders (feeding method used by sponges in which food particles are filtered out from the water - aquiferous systems)

Archeaocytes (within Amoebocytes)

- Like stem cells, not specialized but can differentiate to any needed sponge cell type (most basic sponge cell type) - forms spongin and spicules - brings nutrients to other cell types (nutrient distribution) - amoeba-like cells in between the two layers of cells that move and change shape, involved in digestion, repair of damaged parts, production of eggs, and excretion

Sexual reproduction of sponges

- Most sponges are sequentially hermaphroditic; few separate sexes - Spermatozoa captured by collar cells (which line the inside of the sponge, contain flagella, draw water into the body of the sponge through the pores) - Sperm is secreted, meets with an egg of another sponge - producing gemmules sexually by releasing sperm into water that is taken into another sponge through the collar cells to fertilize the eggs (external fertilization) - sequentialism avoids self-fertilization and promotes cross-fertilization for genetic diversity - sperm arise from choanocytes - eggs usually arise from amoebocytes or choanocytes - can fertilize externally or internally - larvae are lecithotrophic (eat yolk, for most sponges, mom provides energy to larvae) or planktotrophic (can feed) and swim until they find a nice place to grow

Types of amoebocytes in sponges

- Myocytes (contractile cells) - Chromocytes (pigment-building cells) - Sclerocytes (hard cells that merge to build spicules) - Spongocytes (build spongin filament) - Rhabdiferous cells (rod cells to build mesoglea, jelly-like material) - Collencytes and Lophocytes (create collagen for structural integrity) - Archeocytes

Pinacocytes

- Outer sponge cells; thin, leathery and tightly packed together and collectively form the "pinacoderm" - thin, flat cells that line the outer surface of a sponge

Gemmules

- Packets/clusters of amebocytes encased in protective coats made by freshwater sponges - seedlike particles formed during adverse conditions that contain sponge cells protected by spicules that will survive the environmental changes like freezing conditions, when conditions improve they grow into new sponges

Ostia

- Pores of a sponge (sing. Ostium) - opening to spongocoel that is surrounded by porocytes

Synapomorphies

- aquiferous system (big system of channels and pores) - suspension feeders - structural integrity: skeleton of spicules and spongin (organic rubber material, collagen fibres)

Class Demospongiae

- largest class (95% of all sponge spp.) - nearly all are leuconoid - supporting spicules and fibres may be composed of spongin, silica (SiO2), or both but NEVER CaCO3 - includes all freshwater sponges - never 6 rayed - fat, full of spongin

endopinacocytes

- line inner surface of sponge and canals - can trap the largest of food particles entering the sponge in incurrent canals by phagocytosis

Feeding and digestion

- microvilli (increase surface area to catch more food) of choanocyte collar trap smaller food particles (like bacteria) - larger food particles trapped between choanocytes - choanocytes take up food by phagocytosis and start digestion in the food vacuole - choanocytes push water into side of collar and push water out of the collar; flagella drive water across the collar - partially digested food passed via food vacuole to archeocytes/amoebocytes for other parts to feed (to complete digestion) - archeocytes move through mesohyl and transport nutrients to other cells - pinacocytes can also perform phagocytosis sometimes but food is mostly engulfed by choanocytes - digestion is intracellular and occurs within food vacuoles inside cells

Symplesiomorphies

- multicellular but no organs - no neurons - generally asymmetrical as adults - most cells are totipotent (capable of segregation and re-aggregation)

Gas exchange, osmoregulation and excretion

- nitrogenous wastes excreted as ammonia by simple diffusion at individual cell level (no specialized excretory system) - gas exchange by simple diffusion (they don't have lungs/gills) - occurs across choanoderm

Porocytes

- only in asconoids - tubular cells (basically cylindrical pinacocytes) that allow water to flow from the outside of the sponge to its central cavity - form ostia - contractile but no actin or myosin

Benefits of sponges

- provide homes for other animals - used in some medicines - dolphins "sponging" while fishing to protect their snouts

Reproduction

- same sponge can release sperm and then catch sperm from another sponge to fertilize its eggs (hemaphroditic) - protandric (first male, then female) life history - sperm from the same species is ingested, pushed into mesohyl, where fertilization occurs - sperm from different species is just ingested as food - no gonads in sponges (sperm from choanocytes and eggs from amoebocytes in mesohyl)

Water flow

- slowest through choanocyte chambers to maximize food absorption - the choanocyte chamber has a higher total cross-sectional area than the oscula or any incurrent openings - fastest flow going out osculum to move waste away from sponge so that waste is not taken back in - constricting osculum and excurrent canals makes water go whoosh

Choanocytes

- specialized cell in sponges that uses a flagellum to move a steady current of water through the sponge - flagellated collar cells, generate a water current through the sponge and ingest suspended food - increase surface area of sponge --> better nutrient distribution, bigger sponges are less likely to be eaten - sperm arise from choanocytes - involved in feeding, gas exchange, and fertilization process

osculum

A large opening on the top of a sponge through which filtered water and waste are expelled from the body

indirect life history (r-selected, low-cost zygote, low survival, wide distribution/dispersal, low parental care)

Adults (sexually mature) --> gametes (may be eaten by other animal and die but some manage to survive) --> free spawn --> external fertilization --> zygote --> larvae (moves away from parent, leaves through osculum) --> metamorphosis --> juvenile --> adult (cycle then repeats)

mixed life history

Adults (sexually mature) --> gametes (may be eaten by other animal and die but some manage to survive) --> modified mixed: free spawn which leads to internal fertilization (sperm enters female sponge through aquiferous system) --> zygote --> larvae (moves away from parent, leaves through osculum) --> metamorphosis --> juvenile --> adult (cycle then repeats)

direct life history (k-selected, high-cost zygote, high survival, narrow distribution, high parental care)

Adults (sexually mature) --> gametes --> internal fertilization --> zygote --> juvenile --> adult (cycle then repeats)

Reproduction

Asexual AND Sexual

Symmetry

Asymmetrical (as they don't have true tissues)

Skeletons of porifera are used for?

Bathing and scrubbing

Stages of development (sexual reproduction)

Blastula > Larvae > Adult

How do sponges get their food

Choanocytes trap food and bring it down into the sponge

Amoebocytes

Found in sponges, these cells are mobile and perform numerous functions, including reproduction, transport of food particles to non-feeding cells, and secretion of material that forms the spicules

Class Spongillidae

Freshwater Sponges

Where do they live?

Marine and freshwater (stuck to rock, leaf, other organisms)

Where does sexual reproduction of sponges take place

Mesohyl: contains gametes and amoebocytes

Do sponges have any embryonic germ layers?

No, since they don't have true tissues/basement membrane

Flow of water through a sponge

Ostia > Canals > Spongocoel > Osculum

Porifera

Pore-bearer; they form large networks to hold the ecosystem together (give other animals shelter); they fill their bodies with sharp glass/CacO3 spicules and nasty chemicals to evade predators

What is important about gemmules formation?

Provides protection from a harsh environment before a blastula is formed

Phylum Perifera includes which animals?

Sponges

Mesohyl

a gelatinous region (type of mesenchyme) between the choanocytes and the pinacocyte containing cells, spicules, and mesoglea

choanoderm

a type of cell layer composed of flagellated collar cells, or choanocytes found in sponges

Reduction bodies

dormant, resistant cyst made by marine and freshwater (more important here) sponges that are less hardy gemmules that can withstand harsh conditions

Internal fertilization

females capture sperm in choanocytes which lose flagella and collar and then migrate through mesohyl to go to the egg

Spongin is used for what?

flexibility of the sponge

sponge ecology

food for some tropical fishes and turtles, common habitats for worms, fishes, shrimp form symbiotic relationship with green algae, live on some molluscs to provide camouflage

When are sponges motile?

in larvae stage after sexual reproduction

spongocoel

large central cavity of the sponge

exopinacocytes

line outer surface of sponge for protection

basopinacocytes

line the bottom of the sponge and attach it to surfaces

Body structure

no true tissues/basement membrane, no organs, contain 2 layers of cells with a jellylike substance in between (mesoglea)

Budding

part of the sponge falls off to create a new, genetically identical sponge

regeneration

parts of a sponge will grow back (thanks to amebocytes)

Sessile

permanently attached to a substrate, organism is attached to one spot, does not move

Gland cells

secrete mucus (protection)

Spicules

small needlelike structures made from archaeocytes that are supporting structures of the sponge, made of calcium carbonate, silica, or spongin; protect from predation

External fertilization

smoking sponges - group of sponges coordinate and release gametes at the same time (related to lunar cycle) to meet in the water and fertilize

relationship with humans

sponges with spicules of spongin are used for household scrubbing purposes, medical research focused on chemicals that discourage prey and prevent infections