marine invertebrates 1. marine biodiversity heterotrophs –protista/protozoan phyla –porifera...

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


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


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


Zooxanthellae

Unicellular algae


Some are light producing

Luciferin + O2 = oxyluciferin + light

“Bugler Alarm Theory”

Unicellular algae


Algal blooms are source of “red tides”Can release toxic substances and contaminate fisheries

Unicellular algae


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


Two body forms – in most species

• Medusa - Planktonic Form


• 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

marine invertebrates 1. marine biodiversity heterotrophs –protista/protozoan phyla –porifera...

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