phylum porifera Flashcards
what type of feeders are sponges ?
almost all suspension feeders (filter feeders)
exception to suspension feeding sponges
cold water deep carnivorous sponges - Chondrocladia grandis
prey on planktonic crustaceans
what is multicellularity ?
a condition or state of having or being composed of many cells — with more than one cell type performing different functions
possible evolutionary progression of multicellularity characteristics
- cell adhesion (cells become selective)
- cell specialization and interdependence
- embryonic differentiation
what are the advantages of multicellularity? why did it develop ?
- cells can perform all life functions more efficiently due to specialization
- larger body sizes and more complex body types can be achieved w this, positive competitive advantage
- the diversity of body sizes and types opened up much larger range of habitat niches (not avail to unicellular) - in relation to temp, pH, chemical availability etc)
metazoan tissue types
- epithelial tissue
- connective tissue
- nervous tissue
- muscle tissue
- gametogenic tissue
defining characteristics of epithelial tissue
- forms tight and regular cell sheets (cellularity)
- have a dictated direction (polarity)
- is surficial layer for other cells (attachment)
- have no blood cells (avascular)
- show rapid growth (regeneration)
functional importance of epithelial tissue
- transitional covering on all internal and external surfaces on body
- lines body cavities and hollow organs - is the major tissue in glands
- performs protection (skin), secretion (glands), absorption, excretion, filtration, diffusion, and sensory reception
connective tissue defining characteristics:
- formed by an abundant intercellular matrix with relatively few connecting cells
- contains collagen (the main structural protein - most abundant protein in mammals) — whats being released when making bone broth
functional importance of connective tissue
- binding and holding other tissues together
- supporting and protecting individuals organs
- provides elasticity for movement (ex// cartilage)
defining characteristics of nervous tissue
- ropelike linear or branching bundles in structure
- fibers are excitable - capable of sending and receiving electrochemical signals
- comprised of neurons and neuroglial cells - glial cells supporting the neural structures
functional importance of nervous tissue
- generate and conduct sensory or motor impulses between the brain or spinal cord
- provides all parts of the body w information, and controls both voluntary (movement) and autonomous body functions (digestion)
defining characteristics of muscular tissue
- ability to shorten and lengthen
- highly cellular and highly vascular (supplied well w blood vessels)
- often have elongated nuclei
functional importance of muscular tissue
- contractions produce movement of body parts
- must work w nervous tissue for stimulus
- used for heat generation and fluid distribution functions (ex// blood)
defining characteristics of gametogenic tissue
- haploid (n) or one set of chromosomes. ONLY tissues that are haploid
- produced by dedicated diploid (2n) germ cells which undergoes meiosis that forms haploid cells
- typically sexually dimorphic — male gamete smaller in size and motile — female gamete several times bigger and non-motile
functional importance of gametogenic tissue
- for reproduction only
- combines w another haploid cell at fertilization
- can generate genetic variation among progeny - may allow for faster adaptation of the population to novel and/or stressful environments
— evolution stems from this - genetic variation
how many sponge classes are there ? what are they ?
3
- class calcerea (grantia)
— have hard spicules composed of calcium carbonate (concrete) - can still be flexible - class hexactinella (glass sponges)
— have hard spicules composed of silica dioxide - like glass (not flexible) - class demospongiae (haliclona, halichondria)
— NO spicules - dominant structure of spongin (bath sponges)
habitat and lifestyle of a sponge
- both marine and freshwater
- larval as juveniles, sessile as adults
- hydraulic suspension feeders
- circulating TONS of water all the time
sponge feeding
- small pores lead to complex system of channels lined w specialized feeding cells — called choanocytes or collar cells (pump water in)
sponge morphology and tissue type
- no “true tissues” — like nervous tissue or muscle tissue
— sponges are the only metazoans without these - although they do have different inner and outer tissues
- no specialized digestive system, no nerve tissue, no muscle tissue, no ovaries or testes
- gametes produced by choanocytes
— most are hermaphroditic, and can ALSO reproduce sexually
what are choanocytes and what do they do ?
choanocytes are specialized feeding cells within protoepithelial tissue.
they pump water in, produce gametes, capture and absorb nutrients (collar)
components of a choanocyte
flagellum - moves water thru sponge
collar - not really moving, just at base — filter water w microvilli
— capture and absorb nutrients
cell body - adhering to sponge
external sponge morphology component
pinacocytes
— external cells forming solid sheets (like an epithelium)
— directs water into channels thru negative pressure
— can expand or contract slightly to alter size shape of sponge
2 differences between choanocytes and pinacocytes
choanocytes have flagellum that line interior of sponges — pinacocytes are flat cells in the outer most layer of sponges
choanocytes help to accumulate oxygen and nutrients — pinacocytes provide a shape to body of sponge
sponge morphology: cell type arrangements across body plans (3 body types and matrix)
asconoid - synconoid - leuconoid
increasing complexity from left to right
- asconoid - shaped like a simple tube
- synconoid - now w choanocyte lined radial canals
- leuconoid - now w a complex system of branching inhalant and exhalant canals leading to and from choanocyte chambers
mesohyl : the gelatinous matrix within a sponge
demospongiae: where are they found, structure, what are they used for ?
only class found in freshwater
contain siliceous spicules and/or spongin structure
most abundant ~ 80% of all sponge species
used for bath sponges - huge industry
what happened to sponges ? - downfall and action to try and make them come back
collected by wading and boats in shallow water collected w poles
eventually were only left in deep water — greek divers going after these
take action:
1. legislation
2. aquaculture
3. violence and intimidation
4. fished harder
the last remaining sponges hit by disease — the sponges have no recovered**
this effected sponges, turtles, sharks, shrimp, lobster as well
how did the sponge extraction manifest in biology ?
have evolved chemical and structural defence mechanisms to avoid predation and compete w other benthic organisms like coral
what specifically feeds on sponges?
hawksbill turtle can ingest the “glass” contents— even tho they prefer to feed on non toxic sponges
the historical observation demonstrates the internal biological impacts of extreme reduction in hawksbill turtle populations
overfishing and sponge/coral dynamics
overfished sites had way more overgrowth of corals by sponges — where lacked parr
conclusions : ecological dimensions of sponges
- sponges and all organisms exist in dynamic ecological and human systems
- changes to populations alter ecology which can further impact individual or population biology
- historical ecology opens up a lot of questions
