marine invertebrates 1. marine biodiversity heterotrophs –protista/protozoan phyla –porifera...
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Marine Invertebrates 1
Marine Biodiversity
• Heterotrophs– Protista/Protozoan phyla– Porifera– Cnidaria– Platyhelminthes– Mollusca– Annelida– Arthropoda– Echinodermata– Chordata– As well as numerous smaller phyla
• Bacteria• Unicellular algae
Domain Bacteria
• Cell membrane, but no nucleus and most other organelles• Most abundant form of life, found in every marine environment
o Breakdown of organic material – decay bacteriao Primary production, photosynthesis - cyanobacteria
Domain BacteriaUnique marine functions
Symbiosis - guts of many organisms
Shipworms – are bivalve molluscs not wormsBacteria break down cellulose
Domain BacteriaUnique marine functions
Symbiosis - light production (bioluminescence) in some species
Vibrio – found in high numbers in photophores,contain the oxidative enzyme Luciferin
Luciferin + O2 = oxyluciferin + light
- Are free living and are pulled in photophores when needed
Domain BacteriaUnique marine functions
Symbiosis - toxin production
Tetrodotoxin – neurotoxin with no known antidoteBlocks sodium channels
Unicellular algae
Diatoms
Important primary producers in open water temperate and polar regions- Account of a large portion of O2 produced on Earth
Enclosed in cell walls made of silica
Unicellular algae
Diatoms
Large deposits = diatomceous earth/diatomite
Many uses - fluid filters (beer, swimming pools), insecticides, stabilize dynamite,mild abrasives like toothpaste
Unicellular algae
Phylum Dinoflagellata - Dinoflagellates
• ~ 1200 species, almost all are marine• Important primary producers in warm or tropical waters, some ingest food• Have two flagella, some with plate-like cell walls
Unicellular algae
Phylum Dinoflagellata - Dinoflagellates
Zooxanthellae
Unicellular algae
Phylum Dinoflagellata - Dinoflagellates
Some are light producing
Luciferin + O2 = oxyluciferin + light
“Bugler Alarm Theory”
Unicellular algae
Phylum Dinoflagellata - Dinoflagellates
Algal blooms are source of “red tides”Can release toxic substances and contaminate fisheries
Unicellular algae
Phylum Dinoflagellata - Dinoflagellates
Can release toxic substances and contaminate fisheries
Accumulation in large predators can lead to ciguetera poisoning
Phylum Porifera
Approximately 5000 species worldwide, can dominate benthic habitats ( ~ 1000 species know from tropical reefs)
One of the few groups that have nearly equal diversity in Carribean and Indio-Pacific regions
Mostly marine (98%), some freshwater species (found in Illinois)
Have multiple cell types, but lack tissue
Phylum Porifera
Get their shape from either calcareous spicules or spongin, some species have both
Phylum Porifera
Get their shape from either calcareous spicules or spongin
possess specialized cells called choanocytes
choanocyte
Phylum Porifera Three basic body plans
Asconoid Syconoid Leuconoid
Phylum Porifera
Can reach very large sizes
reproduce both sexually and asexually
sexual reproduction has larval stage = amphiblastula
Evidence of self-recognition
a few species are mobile
some chemically dissolve and cause coral etching
Phylum Cnidaria
• a.k.a Coelenterata or Radiatahydras, jellyfish, sea anemones, corals
• Approx. 10,000 species, found worldwide, mostly marine
Cnidarian Classification
• 3 Classes• Hydrozoa -
• Scyphozoa
• Anthozoa - sea anenomes, corals - all marine
Phylum Cnidaria
Have radial symmetry Have 5 cell types and tissue level of organization Have rudimentary organs Usually have specialized stinging cells -cnidocyte - whole cell
nematocyst - stinging capsule within
cnidocyte
Phylum Cnidaria
• The cnidarian body wall has 3 basic layers (2 tissue layers)
– Epidermis- outer layer– Gastrodermis- lines the
gastrovascular cavity– Mesoglea- between the two
tissue layers; it is a non-cellular gelatinous layer, not a tissue
5 Cell Types
• Epithelio-muscle cells• Cover and protect• Can contract (muscular
properties)• Interstitial cells
• Production of gametes• Mucous secreting cells (Gland cells)-
mucous for attachment, feeding• Cnidocytes- protection, predation• Nerve cells- irritability
Cnidarian life-cycle
Two body forms
• Polyp - Sessile Form
Cnidarian life-cycle
Two body forms – in most species
• Medusa - Planktonic Form
Cnidarian life-cycle
• Both asexual and sexual reproduction• Larvae called Planula
Phylum Cnidaria
nematocysts
Toxicity of cnidarian venom
Over 10,000 different types of toxins identified
Usually a mixture of hemotoxins, neurotoxins, cardiotoxins/musculotoxins
Toxicity ranges from mild stinging to fatal in humans
Portuguese Man O’ War Physalia
Responsible for numerous “attacks” every year off the US coast
Rarely fatal due to low level of venom injected, intense cutaneous pain - most deaths due to drowning
Concentration of venom
Let
hali
ty
Toxicity of cnidarian venom
Box jellyfish or sea wasp Chironex Can reach 3 m in length, found circumtropically, but most common in South Pacific
If not treated immediately you’re toast - one individual contains enough venom to kill 60 humans Responsible for more deaths in Australia than sharks or snakes (one every two years) - 20-40 per year in other regions of Pacific
Cnidarian Classification
• 3 Classes•Hydrozoa - both polyp and medusa stage,
freshwater and marine, polyp stage dominate
• Fire corals - not true coral since the have both polyp and medusa stage
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