Lecture 15 Flashcards
Sub Phylums in Phylum Arthropoda
- Subphylum Chelicerata
- spiders, ticks and mites, horseshoe crabs, scorpions, etc…
- Subphylum Myriapoda
- millipedes, centipedes
• Subphylum Crustacea
• lobsters, crayfishes, shrimp, crabs, water fleas, copepods, and
barnacles
- Subphylum Hexapoda
- Mainly insects: butterflies, bees, wasps, flies, beetles, moths, etc…
Phylum Arthropoda characteristics
3 germ layers coelomate or eucoelomate protostomia, scdysozoa blastopore--> mouth complete gut mostly sexual reproduction bilateral symmetry
Adaptations of Arthropods (6)
- Versatile exoskeleton
- Segmentation and specialized appendages
- Air piped directly to cells
- Highly developed sensory organs
- Complex behaviours
- Trophic breadth through metamorphosis
Exoskeleton
- Exoskeleton = external skeleton
- called the cuticle in arthropods and nematodes
- Cuticle is secreted by the underlying epidermis
- The cuticle contains chitin, a nitrogenous polysaccharide
The cuticle is….
• heavy limits body size • hard and waterproof great protection • Thin and flexible between segments permits free movement of joints
Molting
• Exoskeleton doesn’t expand
• To increase body size, arthropods must molt
• Molt = shed old feathers, hair, skin, or shell, to make way for new growth
• Ecdysis = shedding of outer cuticle, as in insects or crustaceans
a more specific term than moult
Defining feature of the clade ecdysozoa
metamerism in arthropods
=segmentation
- Segments often combined or fused into functional groups, called tagmata (sing. tagma)
- Appendages are also often differentiated (swimming, walking, etc)
Tagmata types
- Head
- Thorax (chest)
- Cephalothorax (head + thorax)
- Abdomen
- trunk
Subphylum Hexapoda visual caracteristics
3 pairs of legs
1 pair antennae
3 body parts (head, thorax, abdomen)
sub phylum chelicerata visual caracteristics
4 pairs legs
no antennae
2 bpdy parts (cephalothorax, abdomen)
sub phylum crustacea visual characteristics
8+ legs
2 pairs of antennae
variable body parts
sub phylum myriapoda visual characteristics
18+ legs
1 pair antennae
2 body parts (head, segmented trunk)
Subphylum Hexapoda Classes
Class Entognatha
• Small class, e.g.springtails
• Wingless
• Base of mouth parts enclosed
Class Insecta • Enormous group • Base of mouth parts visible • Usually two pairs of wings on thorax • e.g.butterflies,bees,wasps,flies,beetles,moths...
Chelicerata cephalothoracic appendages
Most have 6 pairs
• 1 Pair of chelicerae (mouthparts)
• 1 Pair of pedipalps (second pair of appendages)
• 4 pairs of walking legs
Types of Circulatory Systems
• Closed circulatory system
Blood is contained within vessels
Vertebrates and some invertebrates
• Open circulatory system
Blood is confined to vessels in only a
portion of circuit through body
Blood mixes with interstitial fluids (i.e. fluids between cells) in the hemocoel
Because it is mixed with fluid, it is properly called hemolymph
Arthropods and some molluscs