Ch 33 part 1
Transcript Ch 33 part 1
Ch. 33: Invertebrates
-Sessile (attached to
-Osculum (large opening)
-Choanocytes (flagellated collar cells)
-Hermaphroditic (produce both sperm and
2.Phylum Cnidaria: hydras, jellyfish, sea
anemones, and coral animals.
cavity (sac with a
(fluid held under
-Polyps and medusa
-Cnidocytes (cells used for defense and prey
-Nematocysts (stinging capsule)
NOT the same as alternation of generations
that occurs in plants as both polyp and
medusa are diploid organisms.
3.Phylum Ctenophores: Comb jellies
-8 rows of
of fused cilia
that use cilia for
(adhesive structures that capture prey)
4.Phylum Platyhelminthes: Flatworms
-Bilateral; no body cavity
-Predators, scavengers, parasites
-Triplobastic; mesoderm but, GVC with only
one opening – pharynx
-Some cephalization – ganglia, eyespots
-Many pathogens (Schistosoma, Cestodidias)
The blood fluke
leading to body
absorb food particles
from their host.
-Tapeworm eggs are
released in feces.
-Contaminated food and
water can infect host.
-Tapeworm larvae encyst
into muscles of host.
5.Phylum Rotifera: are pseudocoelomates
with jaws, crowns of cilia, and complete
-1,800 species, are tiny animals (0.05 to
2 mm), most of which live in freshwater.
-Internal organs in
acts as a hydrostatic skeleton.
also acts as a
-Some rotifers only exist as females,
reproducing more females from unfertilized
-One type of rotifer produce 2 types of eggs:
1. Eggs that produce females
2. Eggs that produce degenerate males that
live just long enough to fertilize eggs.
6.Phylum Lophophorate: Bryozoans,
Phoronids, and Brachipods.
-Molecular data shows that lophophorates are
-Named Lophophores as they all have a
common physical feature: the lophophore.
The lophophore is a horse-shoe-shaped or
circular fold of the body wall bearing ciliated
tentacles that surround the mouth.
-They also have a U-shaped digestive tract
and the absence of a head.
-True coeloms completely lined with
-Bryozoans are colonial organisms:
-Colony is usually
encased in a hard
-Sessile, coral reef
-Phoronids are tube-dwelling marine worms,
1mm to 50 cm long in length.
-Some live buried in sand,
within chitinous tubes.
-The lophophore is extended
with the phoronid is feeding.
It is withdrawn when it feels
-Brachiopods resemble clams and other bivalve
-Dorsal and ventral sides
7.Phylum Nemertea: Proboscis worms known
for the prey-capturing apparatus.
-Resemble flatworms like tapeworms, but have
fluid-filled sacs that resemble a true coelom.
-Sometimes called “ribbon worms”
-Have complete digestive and circulatory
-Proboscis sticky, barbed, or poisonous
8.Phylum Mollusca have a muscular foot, a
mantle, and a visceral mass.
-Slugs, snails, oysters, clams, octopus, and
-Marine and freshwater
-Soft bodied with hard shell; slugs, octopus,
and squids have lost or reduced during their
-Foot: used for locomotion
-Visceral mass: contains the organs
-Mantle: secretes the shell
-Radula: used to scrape up food
-Most mollusks are separated sexes, but some
snails are hermaphrodites.
-The life cycle of many mollusks include a
ciliated larva called a trophophore (also in
(snails and slugs),
3. Bivalvia (clams,
oysters, and other
-Unique among the
brain and nervous
-They also have a
9.Phylum Annelids: Segmented worms
-Two brain-like ganglia in head
1. Oligochaeta (earthworms)
2. Polychaeta (marine segmented worms)
3. Hirudinea (leeches)
-In annelids, the coelom plays a hydrostatic
-Segmentation allows for specialization of body
10.Phylum Nematodes: Roundworms are nonsegmented pseudocoelomates covered by a
-90,000 species (with probably 10x more)
-Size: 1mm to more than 1m
-Lack a circulatory system
-Complete digestive tract
-Move by moving back
and forth due to
-Reproduce sexually with
-Female can lay over
-Over 50 species of nematodes are parasitic to
Trichinella spiralis causes trichinosis when
the nematode worms encyst in a variety of
human organs, including skeletal muscle.
11.Phylum Arthropods: Segmented coelomates
with exoskeletons and jointed appendages.
-Population: 1 billion billion (1018)
-Nearly 1 million species (most successful
-Evolutionary success due to segmentation,
exoskeleton, and jointed appendages.
specialized body parts