Zoology Unit IV: Classification of Animals

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Questions and Answers

What is binomial nomenclature?

Binomial nomenclature is the system of naming organisms with two parts - a generic name and a specific epithet.

What are the two parts of a scientific name in binomial nomenclature?

Kingdom and Phylum

Family and Genus

Genus and Species (correct)

Class and Order

Vertebrates have a backbone, while invertebrates do not have a backbone.

True

Invertebrates can be identified as animals that do not have a ______.

backbone Signup and view all the answers

Match the following classes with their characteristics:

Gastropoda = Have shells and move with a fleshy foot Bivalvia = Have two shells and lack a distinct head Signup and view all the answers

How does asexual reproduction often occur in sponges?

By budding from the parent Signup and view all the answers

Sponges reproduce sexually when specialized gametocyte cells produce sperm and eggs.

True Signup and view all the answers

What distinguishes marine iguanas found in the Galápagos Islands from other reptiles?

ability to dive and forage underwater, feeding on algae and seaweed Signup and view all the answers

What is the class of marine cnidarians known as true jellyfish?

Scyphozoa Signup and view all the answers

Marine mammals are mammals uniquely adapted to life on land.

False Signup and view all the answers

Class Anthozoa do not have a _______ stage in their life cycle.

medusa Signup and view all the answers

Cephalopods are gonochoric.

True Signup and view all the answers

Which of the following are conservation challenges faced by aquatic reptiles?

Pollution Signup and view all the answers

What ecological roles do aquatic reptiles, like sea snakes and marine iguanas, play in their habitats?

contributing to nutrient cycling, regulating prey populations, maintaining biodiversity Signup and view all the answers

Match the following fish classes with their characteristics:

Agnatha = Jawless fish with eel-like body structure Chondrichthyes = Cartilaginous fish with skeleton made of cartilage Osteichthyes = Bony fish with skeletons primarily composed of bone Signup and view all the answers

What is the primary function of the foot in bivalves?

Burrowing Signup and view all the answers

How do bivalves anchor themselves to a hard substrate?

By using their foot and byssus Signup and view all the answers

Match the following marine mammals with their characteristics:

Cetaceans (whales, dolphins, porpoises) = Streamlined bodies, powerful tails, ability to communicate using echolocation Pinnipeds (seals, sea lions, walruses) = Flipper-like limbs, adept at swimming and maneuvering on land Sirenians (manatees, dugongs) = Herbivorous mammals with paddle-shaped flippers, feed on seagrasses in shallow coastal waters Marine otters (e.g., sea otters) = Control sea urchin populations in kelp forest ecosystems Signup and view all the answers

Arthropods have a hard exoskeleton made of a strong polysaccharide called ________.

chitin Signup and view all the answers

Match the following echinoderm classes with their characteristics:

Holothuridae = Long and worm-like, pentaradial symmetry, tube feet, branching tentacles Echinoidea = Spiny, calcareous endoskeleton, Aristotle's lantern Asteroidea = Arms surrounding a central disk, can lose and regrow arms, photoreception, chemoreception Signup and view all the answers

Study Notes

Fundamentals of Zoology

Classification of Animals

The classification of animals is divided into two major groups: invertebrates and vertebrates
Invertebrates lack a backbone, while vertebrates have a backbone or spinal column

Invertebrates

Make up more than 97% of all animal species
Found almost everywhere, from deserts to deep-sea beds
Lack a skeletal system, resulting in a soft and often flexible body
Have an open circulatory system and a simple respiratory system
Often have an external skeleton that protects their soft body, made of chitin

Vertebrates

Make up around 3% of all animal species
Possess a well-defined internal skeleton system, including a backbone
Have more complex and specialized organ systems compared to invertebrates
Have bilaterally symmetrical bodies and a brain enclosed by a skull

Phylum Chordata

Characteristics:
- Notochord (a longitudinal, cartilaginous rod)
- Dorsal nerve cord (a bundle of nerves running along the back)
- Pharyngeal slits (openings that allow water to enter the mouth)
- Post-anal tail (an extension of the body beyond the anus)

Major Phyla of Invertebrates Relevant to Fisheries

Mollusca
- Soft-bodied, triploblastic, and bilaterally symmetrical
- Coelomate, with a thin fleshy envelope or mantle covering the visceral organs
- Classes: Gastropoda, Bivalvia, and Cephalopoda

Class Gastropoda

Second-largest class of animals, with 40,000-90,000 living species
Characterized by:
- Snails and slugs with a soft body, usually protected by a shell
- Foot that spans the length of the body
- Head with a mouth, sensory structures, and eyes

Class Bivalvia

Characteristics:
- Clam-shaped, with a pair of shells (valves) connected by a hinge
- Body laterally compressed, with a soft, flexible mantle
- Gills for respiration and feeding
- Foot that is used for burrowing and anchoring

Class Cephalopoda

Most morphologically and behaviorally complex class in phylum Mollusca
Characteristics:
- Completely merged head and foot
- Ring of arms and/or tentacles surrounding the head
- Strong beak, radula, and salivary glands
- Digestive tract with esophagus, stomach, and caecum
- Ink gland that produces a suspension of melanin

Phylum Arthropoda

Characteristics:
- Jointed legs
- Segmented body
- Hard exoskeleton made of chitin
- Compound eyes
- Reproduce sexually through external fertilization or asexually

Phylum Echinodermata

Characteristics:
- Radial symmetry
- Water vascular system
- Ability to regenerate lost body parts
- Classes: Starfish, Sea Urchins, Sand Dollars, and Sea Cucumbers

Class Holothuridae

Characteristics:
- Long, worm-like body with pentaradial symmetry
- Mouth and anus located on opposite poles
- Five rows of tube feet along the body
- Ten to 30 branching tentacles surrounding the mouth
- Single gonad, with most being dioecious### Phylum Echinodermata
Holothurians (sea cucumbers) crawl using podia or body wall muscles
Some deep-sea species have elongate podia for walking
Trap particles and plankton on mucus-covered tentacles
Secrete mucus from secretory cells and gland cells

Class Echinoidea (Sea Urchins, Sand Dollars, and Heart Urchins)

Includes sea urchins, sand dollars, and heart urchins
Mouth (peristome) is on the bottom, and anus (periproct) is on top
Aristotle's lantern: a five-part jaw apparatus used for breaking apart food and scraping surfaces for algae
Irregular echinoids do not have a lantern, and their mouth is on the bottom, but anus is shifted to the posterior side or bottom of the test

Class Asteroidea (Sea Stars)

Characterized by rays or arms surrounding an indistinct central disk
Arms are hollow, covered with short spines and pedicellariae, and have tube feet for creeping and clinging
Can lose one or more arms and grow new ones
Each arm has an eye spot for sensing changes in light, and tube feet for sensing chemicals, water currents, and objects

Phylum Porifera (Sponges)

Lack true tissues and organs
Simple, multicellular, aquatic animals
Sessile (permanently attached to rocks or other submerged objects)
Skeletal elements are produced by amoebocytes
Sponges can reproduce asexually by budding or sexually by producing gametes

Phylum Cnidaria (Corals, Sea Anemones, Jellyfishes, and Hydras)

Characterized by the presence of cnidae
Cnidarians have a life cycle that includes both sexual and asexual reproduction
Class Scyphozoa (True Jellyfish)
- Characterized by a dominant medusa stage
- Thick, gelatinous mesoglea layer provides buoyancy
- Tentacles are equipped with cnidocytes for capturing prey and defense
Class Anthozoa (Corals, Sea Anemones, and Sea Pens)
- Lack a medusa stage
- Radial symmetry, tubular bodies, and a central mouth surrounded by tentacles
- Cnidocytes are used for capturing prey and defense

Major Classes of Vertebrates Relevant to Fisheries

Class Agnatha (Jawless Fish)

Represents one of the oldest and most primitive groups of vertebrates
Characterized by the absence of jaws and paired fins
Have a cartilaginous skeleton
Breathe through multiple gill pouches
Examples: lampreys and hagfish

Class Chondrichthyes (Cartilaginous Fish)

Skeleton is composed of cartilage rather than bone
Diverse group, including sharks, rays, and skates
Characterized by streamlined bodies, tough skin, and formidable jaws
Examples: Great White Shark, Hammerhead Shark, Manta Ray, and Stingrays

Class Osteichthyes (Bony Fish)

Skeleton is primarily composed of bone
Diverse group, including both freshwater and marine environments
Characterized by the presence of swim bladders and scales made of enamel or ganoin
Examples: salmon, trout, and Clownfish

Aquatic Reptiles

Crocodilians (crocodiles and alligators)
Sea turtles (loggerhead and green turtle)
Marine iguanas (found in the Galápagos Islands)
Sea snakes (venomous reptiles)
Ecological roles: contribute to nutrient cycling, regulate prey populations, and maintain biodiversity

Marine Mammals

Cetaceans (whales, dolphins, and porpoises)
Pinnipeds (seals, sea lions, and walruses)
Sirenians (manatees and dugongs)
Marine otters (sea otters)
Ecological roles: regulate sea urchin populations, maintain kelp forest ecosystems
Conservation challenges: habitat degradation, pollution, climate change, and human activities

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Description

Learn about the major groups of animals, including invertebrates and vertebrates, and understand the principles of taxonomy and modern classification systems.