Invertebrates Class Notes

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Questions and Answers

Which characteristic is exclusive to Chelicerata?

Have a water vascular system

Have two pairs of legs per segment

Have antennae

Have book lungs for respiration (correct)

How many pairs of legs do centipedes possess?

Four pairs per segment

One pair per segment (correct)

Eight pairs per segment

Two pairs per segment

What type of symmetry do adult echinoderms exhibit?

Radial symmetry (correct)

Asymmetrical symmetry

Trilateral symmetry

Bilateral symmetry

Which of the following groups is classified under Hexapoda?

Insects Signup and view all the answers

What feature is absent in Chelicerata?

Antennae Signup and view all the answers

Which characteristic is true for Crustacea?

Two pairs of antennae Signup and view all the answers

What is the function of Malpighian tubules in insects?

Excretion Signup and view all the answers

Which statement about hemichordates is most accurate?

Some are colonial filter feeders. Signup and view all the answers

Which structures are characteristic of the Lophophorate phyla?

Lophophores Signup and view all the answers

What type of locomotion do comb jellies primarily use?

Cilia Signup and view all the answers

What is a feature that distinguishes Ecdysozoa from other animal groups?

The process of ecdysis Signup and view all the answers

Which of the following correctly describes the reproductive nature of sponges?

Both asexual and sexual reproduction Signup and view all the answers

Which of the following developmental patterns is associated with Deuterostomia?

Radial cleavage Signup and view all the answers

What characteristic distinguishes cnidarians?

Radial symmetry Signup and view all the answers

What is a notable characteristic of Tardigrada?

They can suspend their metabolism for extended periods Signup and view all the answers

Which structure is unique to the class of cnidarians?

Nematocysts Signup and view all the answers

How do organisms with incomplete metamorphosis differ from those with complete metamorphosis?

They resemble small adults in their nymph stage Signup and view all the answers

What type of digestive process do sponges utilize?

Intercellular digestion Signup and view all the answers

How do flatworms differ in terms of body structure?

They are acoelomates Signup and view all the answers

In which phylum are the majority of species hermaphrodites?

Porifera Signup and view all the answers

Which of the following is true regarding the embryonic development of ctenophores?

They exhibit unique embryonic development Signup and view all the answers

What unique feature do rotifers possess that aids in their feeding?

A crown of cilia Signup and view all the answers

Which of the following anatomical features is characteristic of the phylum Mollusca?

A radula for feeding Signup and view all the answers

Which statement about nematodes is true?

They are unsegmented round worms. Signup and view all the answers

What distinguishes annelids from other phyla mentioned?

They have a segmented body. Signup and view all the answers

What circulatory system type is found in arthropods?

Open circulatory system Signup and view all the answers

Which characteristic is unique to phylum Nemertea?

Closed circulatory system Signup and view all the answers

What is a key characteristic of mollusks with respect to their circulatory system?

Most have an open circulatory system. Signup and view all the answers

What anatomical feature is found in most, but not all, mollusks?

A protective shell of calcium carbonate Signup and view all the answers

Study Notes

Invertebrates Notes

Phylum Ctenophora (Comb Jellies):
- First animal phylum to diverge from other animals
- All marine, abundant
- Cilia for locomotion, arranged into combs
- Most have 2 long tentacles with sticky hairs
- Gastrovascular cavity for digestion and circulation of digested nutrients
- Hermaphrodites (both male and female reproductive organs)
- Bioluminescent
- Unique embryonic development and nervous system compared to bilateral animals
Phylum Porifera (Sponges):
- Mostly marine
- Mostly no symmetry
- No tissues, potentially a degenerative condition
- Adults sessile, anchored in one place
- Filter feeders (suspension feeders) filtering matter and plankton
- Many specialized cells (flagellated choanocytes) draw water through pores
- Amoebocytes absorb food, digest, and distribute nutrients
- Intracellular digestion (limits food size)
- Sponges have an inner and outer layer of cells with gelatinous material in between
- Mostly hermaphrodites
- Can reproduce asexually and sexually
- Contain a tough protein (spongin) and spicules (silica/calcium carbonate/protein)
Phylum Cnidaria:
- Jellyfish, corals, hydras, sea anemones, box jellies, etc.
- Radial symmetry
- Two tissue layers (ectoderm and endoderm)
- Mostly marine, some in freshwater
- Gastrovascular cavity
- Jelly-like acellular material (mesoglea) between the tissue layers
- Have cells called cnidocytes containing nematocytes that release venom
Phylum Platyhelminthes (Flatworms):
- Acoelomates
- Free-living and parasitic species
- Gastrovascular tract with a single opening
- Free-living forms include planarians
- Most have a distinct head and ventral nerve chords
- Include flukes (parasites) and tapeworms (parasites with no digestive tract—absorb food)
Phylum Rotifera (Rotifers):
- Very small
- Mostly freshwater
- Pseudocoelomates
- Have a crown of cilia directing food into the mouth
- Have jaws to grind food
- Complete digestive tract (mouth and anus)
Phylum Nemertea (Ribbon or Proboscis Worms):
- Coelomates
- A complete digestive tract
- Closed circulatory system (blood in vessels)
- Some are venomous
Phylum Mollusca:
- Soft bodies, many with protective shells of calcium carbonate
- Visceral mass contains most organs
- Mantle folds over visceral mass, secretes shell
- Radula (rasping feeding organ in many, not all)
- Most have an open circulatory system (hemolymph bathes organs)
- Ventral nerve cords
- Includes snails, slugs, clams, oysters, mussels, scallops, squids, octopuses, cuttlefish, and nautiluses
- Most have internal shells
- Have a closed circulatory system
- Have a complex brain
Phylum Annelida (Segmented Worms):
- Coelomates (protostomes)
- Closed circulatory system
- Metanephridia (paired excretory tubules)
- Brain-like cerebral ganglia
- Earthworms are cross-fertilizing hermaphrodites, tubeworms are sessile as adults
- Polychaetes are marine worms with parapodia (structures that look like legs)
Phylum Nematoda (Unsegmented Roundworms):
- Pseudocoelomates
- Important members of zooplankton and important parasites. Very abundant.
Phylum Arthropoda (Jointed Feet):
- Crustaceans, spiders, insects, millipedes, centipedes, many others
- Coelomates (protostomes)
- Jointed legs, hard exoskeleton, segmentation
- Exoskeleton made of chitin and protein (protection and water resistance)
- Molting (shedding old exoskeleton)
- Many sensor organs concentrated on heads. Many appendages. Open circulatory system.
- 4 major subphyla
  - Chelicerata
  - Myriapoda
  - Crustacea
  - Hexapoda
- Chelicerata: arachnids, sea spiders, horseshoe crabs
- Myriapoda: centipedes, millipedes
- Crustacea: crabs, lobsters, shrimp, etc.
- Hexapoda: Insects, have 3 body regions (head, thorax, abdomen), 3 pairs of legs, one pair of antennae.
Phylum Echinodermata (Spiny Skin Animals):
- Deuterostomes
- Starfish, brittle stars, sea urchins, sand dollars, sea lilies/cucumbers
- Water vascular system (hydraulic canals connected to tube feet) for locomotion, feeding, and respiration
- Have a hard skeleton
- Radial symmetry as adults
- Larvae are bilateral
- Closely related to our own phylum. Important members of zooplankton (marine + freshwater).
Phylum Hemichordata (Marine Worms):
- Related to echinoderms and chordates
- Some are burrowing sediment feeders, some are colonial filter feeders
- Features of chordates
- Acorn worms (formerly considered chordates)
Phylum Chordata (include vertebrates):
- This is not an invertebrate phylum.
Other phyla (Lophophorates, Ecdysozoa, Deuterostomia):
- Lophophorates have ciliated feeding structures (lophophore)
- Ecdysozoa have molting outer covering (ecdysis)
- Deuterostomia share similar developmental pattern
Metamorphosis:
- Incomplete: young (nymphs) resemble adults, several molts
- Complete: larval stages, transformation during pupal stage
- Tardigrada (water bears) can suspend metabolism during extreme conditions, such as periods of drought

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Description

Explore the fascinating world of invertebrates with notes on Phylum Ctenophora and Phylum Porifera. Learn about their unique characteristics, such as locomotion using cilia, filter feeding methods, and their developmental differences compared to bilateral animals. This quiz will test your knowledge of invertebrate biology and their ecological roles.