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Invertebrates •  Animals without

backbones •  We’ll cover

characteristics of major phyla and some to class level (KPCOFGS)

•  We’ll also cover some natural history

•  Refer to your notes that I posted on-line!

•  Levels of complexity change (become more complex) as we move ‘up’ the evolutionary tree

•  ‘Ancient’ animals are no better or worse adapted than ‘more complex’ animals. Its all about survival.

Ctenophores here too

Lophophorates

• No real symmetry, associations of loosely aggregated cells - very simple!

• Coanocytes (flagellated), collar cells, allow for food intake and O2. Osculum is excurrent pore (can have several), pore cells intake water

• Skeleton Spicules (CaCO3, or SiO2), or spongin (household sponges)

• Ecology: sessile, benthic, filter feeder. Encrusting and upright, and boring

• Most are hermaphrodites: eggs and sperm (broadcast). Fertilization is internal. Also have asexual reproduction: budding, re-aggregation

Sponges: Porifera ‘pore bearer’ Sponges are Suspension Feeders Choanocytes or Collar cells - flagellated

food-trapping cells of a sponge that generate a current through the pores

Water out through Osculum

Water in through Pore Cells

Water

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Cnidaria •  Radial symmetry –  similar parts of the body are repeated around the

center. No front or back, No head •  Oral surface (mouth side) •  aboral surface (opposite of mouth side)

•  Two Body Forms –  Polyp -cylindrical and usually attached

•  Corals, •  Anemones •  many colonial hydroids

–  Medusa - umbrella-like swimming form •  upside-down polyp adapted for swimming

Polyp

Medusa

Feeding Polyps on colonial hydroid

Phylum Cnidaria

•  Diverse forms: jellyfish, corals, anemones, sea fans etc. Stinging cells = nematocysts

•  Gastrovascular cavity digestion and absorbtion of nutrients. Waste through mouth! Respiration occurs through diffusion.

•  Hydrostatic (water) skeleton •  Ecology: sessile and benthic, as well as free swimming

(planktonic). Filter feeders and predators. Some are colonial animals. (corals, sea fans, gorgonians, man-o-war). Some like man-o-war and by the wind sailors have sails to aid in movement!

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Phylum Cnidaria

•  Symbiosis is common with zooxanthellae: 95% of food and formation of calcareous skeleton.

•  Sex: Two phase life cycle (polymorphism)=sessile polyp phase and mobile medusa phase. Sexual rep is usually by medusa (eggs and sperm by broadcast spawning, or internal fertilization). Polyp also undergoes asexual budding

Phylum Cnidaria

•  Some have a two phase life cycle! Polyp and medusa

Phylum Cnidaria

•  Some have a two phase life cycle! Polyp and medusa

Aurelia: one of ‘our’ Jellyfish (scyphozoan)

Phylum Cnidaria Class Hydrozoa:�siphonophores

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Phylum Cnidaria - Class Hydrozoa Phylum Cnidaria, class scyphozoa�Jellyfish and friends

Stinging cells - unique to Cnidaria

Fluid filled capsule

•  Nematocysts discharge on contact and with other stimuli (e.g. fresh water!)

Nematocysts

Anthozoa - corals and anemones

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Coral Polyp •  Zooxanthellae

–  photosynthetic dinoflagellates (Kingdom: Protista) that are adapted to live within corals.

Mouth

Tentacles

Gut

Zooxanthellae

Phylum Cnidaria - Class Anthozoa

Metridium giganteum, Urticina lofotensis, Urticina piscivora White plumed anemone, White spotted rose a., Fish eating anemone

Phylum Ctenophora Phylum: Ctenophora

•  Characteristics of Comb Jellies  About 100 species - more????  8 rows of ciliary combs (ctenes)  Bi-radial symmetry  Cilia beat continuously

•  Light is refracted off the cilia giving a prism-like color effect

 Respiration occurs at body surface  some have tentacles with sticky cells called

colloblasts used to capture prey  cells and tissues are organized into organs

(rudimentary)  simple Gut (single opening)

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Phylum: Ctenophora •  Natural history of Comb Jellies

–  No segmentation; No circulatory system

–  length from a few mm (sea gooseberry) to 2 meters long (venus’s girdle)

–  Most are pelagic, Found in warm and cold oceans - many are deep sea and bioluminescent

–  Carnivores (e.g. eat fish larvae) –  Hermaphrodites – broadcast –  Lots we don’t know!

Flatworms:�Phylum: Platyhelmenthes�

Class Turbellaria

Phylum Platyhelminthes: flatworms

• As many as 20,000 species! • CNS, Brain (agg. Of nerve cells in head region).

Nerve cords and muscular system. • Many (such as flukes) are parasites (eg.

tapeworms – one is 40 feet long – in sperm whales)

• Bilateral • Organs and organ systems, nerves, brain, CNS,

muscles • No skeleton • Variety of functions (parasites, free living etc.) • Sexual, most have larval stage

Flatworms:�Phylum: Platyhelmenthes�

Class Turbellaria

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Ph Nemertea (ribbon worms),� Ph Nematoda (roundworms)

Phylum Nematoda (roundworms) •  Bilateral symmetry •  dig tract, and true organs. •  Hydrostatic skeleton •  Huge #s in sediments, decomposers, parasites, •  Sexual reproduction with larvae. •  Can be seen in fish flesh!

Lophophorates: bilateral symmetry

Bugula turbinata

Lichenopora hispida

Plumatella fungosa

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Lophophorates: Lophophore=set of ciliated tentacles arranged in a horseshoe).

•  Suspension feeders, mostly colonial (individual zooids), live in area of low sedimentation

•  Bilateral •  Unsegmented, colonial. U shaped gut •  Exoskeleton of a variety of shapes •  Benthic filterfeeders •  Sexual and asexual.

•  Phylum Bryozoa: look like colonial hydrozoans. 4000 species, delicate colonies. Retractable lophophore. Zooids show task specialization.

Bryozoans (moss animals)

Polychaete worms (Phylum Annelida)

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Phylum Annelida: segmented worms

•  bilateral •  Segmentation •  Gut cavity, complex movement and systems. Makes them

good crawlers and burrowers. •  2 Ventral nerve cords : peristaltic movement. Each

segment has ‘kidneys’ for nitrogenous waste, and parapodia with setae for movement.

•  Closed circulatory system. •  Have gills •  Hydrostatic skeleton - many have tubes etc! •  See ploychaeta: deposit feeders and suspension feeders:

active and passive, and carnivorous. Some crawl. •  Sexual. Trochophore larvae. often timed with phases of

moon.

Diopatra ornata Ornate Tube Worm

Phylum Annelida - Class Polychaeta

Class Polychaeta: most annelid species are here. 6,000 sp. Mostly marine. 5-10 cm long. Live singly or in aggregations. Build tubes made with lots of different things. Cilia and mucus aid in feeding.

Phylum sipuncula: peanut worms Phylum Sipuncula (peanut worms). • All marine. 350 sp, benthic. Most intertidal, few

deep sea. • Bilateral • Unsegmented. Can curl in to look like peanut.

Mouth and anus at same end • Hydrostatic • Burrows (open at one end). Calcarous tubes or

burrows. • Sexual: gametes released through temporary

gonads. External fertilization

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Ph. Echiura: fat innkeeper worm Phylum Echiura: spoon worms. About 100 sp. Fat innkeeper (Urechis Caupo). Burrow with

commenal creatures in mud. Sweep detritus with proboscis and urechis uses a mucus net. Pumps water through burrow and through net. Close relatives of annelids.