Questions and Answers
What is Phylum Arthropoda?
Paired jointed appendages, rigid exoskeleton made of chitin; fused & modified segments as well as enhanced sensory organs for sight & smell.
What does Class Malacostraca refer to?
Crayfish
What is serial homology?
When similar structures evolve from the same primitive structure.
What does biramous mean?
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What is ecdysis?
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What is the function of a statocyst?
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What does uniramous mean?
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What is the carapace?
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What is a rostrum?
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What is a maxilliped?
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What are swimmerets?
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What is a uropod?
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What do seminal receptacles do?
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What are chelipeds?
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How many walking legs do crayfish have?
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What is the first pair of walking legs called?
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What is a mandible?
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What is the heart in an arthropod?
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What are gastric muscles?
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What are extensor muscles?
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What are flexor muscles?
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What is an antennal gland?
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What is the function of the intestine in crayfish?
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What is branchiostegite?
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What are antennae?
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What is the abdomen in crayfish?
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What is the telson?
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What are copulatory swimmerets?
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What is the opening of the oviduct?
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What are antennules?
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What is the gill bailer?
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What are gills?
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Where is the stomach located in crayfish?
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What are mandibular muscles?
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What is the digestive gland?
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What are gonads?
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What are gastric teeth?
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Study Notes
Phylum Arthropoda
- Characterized by paired jointed appendages, a rigid exoskeleton made of chitin.
- Features modified and fused body segments with advanced sensory organs for enhanced sight and smell.
- Considered the most successful animal phylum due to the vast number of species.
- Includes significant food sources such as lobsters, crabs, shrimps, and crayfish.
- Identification based on the arrangement of appendages and body segments.
Class Malacostraca
- Includes crayfish, a subclass of crustaceans.
Serial Homology
- Refers to the evolution of similar structures from a common primitive structure.
- In crayfish, examples include chelipeds (claws), pereiopods (walking limbs), pleopods (swimming limbs), and uropods (tail fins).
Biramous vs. Uniramous
- Biramous: appendages with two branches.
- Uniramous: unbranched appendages.
Ecdysis
- The process of periodic shedding or molting of the outer cuticle layer.
Statocyst
- A sensory organ responsible for balance and equilibrium.
Anatomical Features of Crayfish
- Carapace: protective shield-like plate covering the cephalothorax.
- Rostrum: snout-like projection on the head.
- Maxilliped: appendages behind the maxilla used for touch, taste, and manipulating food.
- Swimmerets (pleopods): small legs aiding in swimming.
- Uropod: located on the sixth abdominal segment, part of the tail fan for propulsion.
Reproductive Structures
- Seminal receptacles: store sperm from mating crayfish.
- Opening of oviduct: situated between the second pair of walking legs, above the seminal receptacle.
- Copulatory swimmeret: the first pair of swimmerets used during mating.
Muscular and Digestive Anatomy
- Heart: a hollow muscle pumping blood throughout the body.
- Gastric muscles: enable the stomach to grind food.
- Intestine: a straight line extending from the stomach.
- Digestive glands: large organs responsible for digestion, larger than the stomach and heart combined.
- Mandibular muscles: responsible for moving the mandible for feeding.
- Gastric teeth: within the stomach, used to grind food part of the gastric mill.
Appendage Details
- Walking legs: 10 total, arranged as 5 pairs located on the ventral side of the cephalothorax.
- Chelipeds: specialized pincers used for seizing and crushing prey.
- Antennules: short pair of sensory antennae for touch and taste.
- Antennae: longer sensory structures detecting air movement and vibrations.
Gills and Breathing
- Gills: fern-like structures lining the sides of the carapace, essential for respiration.
- Gill bailer: a structure used to expel water from the gill cavity, aiding in respiration.
Movement and Coordination
- Extensor muscles: increase the angle at joints, such as straightening the elbow.
- Flexor muscles: decrease the angle at joints, like bending the arm.
Specifics on Crayfish
- Crayfish possess 10 walking legs; the first pair are called chelipeds.
- The abdominal section begins after the walking legs and extends to the end of the crayfish.
- Telson: the tail section utilized for backward propulsion.
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Description
Test your knowledge on Phylum Arthropoda, focusing on its characteristics, significance, and classification. This quiz also delves into Class Malacostraca, examining key concepts like serial homology, appendage types, and ecdysis. Perfect for students of biology wanting to understand crustaceans better.