Transcript IB 362 invert. lecture 1

Marine Invertebrates 1
Marine Biodiversity
• Bacteria
• Unicellular algae
• Heterotrophs
– Protista/Protozoan phyla
– Porifera
– Cnidaria
– Platyhelminthes
– Mollusca
– Annelida
– Arthropoda
– Echinodermata
– Chordata
– As well as numerous smaller phyla
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 bacteria
o Primary production, photosynthesis - cyanobacteria
Domain Bacteria
Unique marine functions
Symbiosis
- guts of many organisms
Shipworms – are bivalve molluscs not worms
Bacteria break down cellulose
Domain Bacteria
Unique 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 Bacteria
Unique marine functions
Symbiosis
- toxin production
Tetrodotoxin – neurotoxin with no known antidote
Blocks sodium channels
Unicellular algae
Diatoms
Enclosed in cell walls made of silica
Important primary producers in open water temperate and polar regions
- Account of a large portion of O2 produced on Earth
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 Radiata
hydras, 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 noncellular 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
Lethality
Concentration of venom
 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
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