Final Theme Topics 23-28

Adaptations of terrestrial eukaryotes

• Water retention: Waxy cuticles, stomata, roots

• Support: Rigid cell walls, lignin, skeletons

• Reproduction: Internal fertilization, seeds, and pollen

• Temperature regulation: Behavioral and physiological adaptations

• Gas exchange: Lungs, tracheae, stomata

• Desiccation resistance: Protective coatings, dormant stages

Metamorphosis

Arthropods → many insects go through metamorphosis during their development

• Incomplete metamorphosis → juveniles (nymphs) resemble small adults; they go through a series of moults other than reach full size

• Complete metamorphosis: have a larval stage (maggot, grub, or caterpillar); wings develop in one step in the pupal stage.

Characteristics of chelicerates

• Have claw-like feeding parts called chelicerae

• Body divided into cephalothorax (with carapace & 6 appendage pairs) and abdomen (no appendages)

• No antennae

• Chelicerae: 2–3-segment pincers before the mouth

• Spiders: use venomous chelicerae + silk spinnerets

• Scorpions: pincers = pedipalps, stinger on tail

• Mites: tiny, fused body, many roles (predators, parasites, etc.)

Differentiating between arthropods using characteristics

• Trilobita: Extinct, biramous limbs.

• Chelicerata: No antennae, chelicerae (claw mouthparts).

  • Spiders: venom + silk.

  • Scorpions: pincers + stinger.

  • Mites: tiny, diverse.

• Myriapoda: Many-legged land dwellers.

  • Millipedes: 2 legs/seg, herbivores.

  • Centipedes: 1 leg/seg, predators.

• Crustacea: Marine, 2 antennae, biramous limbs, gills.

  • Ex: crabs, shrimp.

• Hexapoda (Insects): 6 legs, wings (often), metamorphosis, tracheal breathing.

Characteristics of Echinodermata

• Radial symmetry (larvae bilateral).

• Endoskeleton of calcareous ossicles.

• Water vascular system (tube feet) for movement/feeding.

• No brain, diffuse nerves.

• Separate sexes, external fertilization.

Characteristics of Chordata

• Notochord: flexible rod for skeletal support.

• Dorsal nerve cord: hollow, from ectoderm.

• Pharyngeal slits: for filter-feeding, gas exchange, or head/neck structures.

• Post-anal tail: muscular, for movement; reduced in some.

• Vertebrates and invertebrates

• Part of deuterostomia

Differentiating between clades of chordates

Clade Vertebrata → all animals with backbones

Clade Osteichthyans → vertebrates with bones (not cartilage like sharks) and lungs/lung-like organs

Clade Gnathostomes → opposing jaws )open close_, two pairs of lateral appendages (fins/legs), most vertebrates

Reproductive modes

• Oviparous: Eggs laid outside; embryo nourished by yolk.

• Ovoviviparous: Eggs hatch inside; nourished by yolk, not mother.

• Viviparous: Embryo develops inside; nourished via placenta.

Characteristics of Actinopterygii (monophyletic)

• Clade osteichthyans

• Fins are supported by elongated, flexible bony rays

  connected to basal, bony elements.

• Includes the vast majority (>99%) of bony fish species

• Ray-finned fish

Characteristics of Sarcopterygii (paraphyletic)

• Lobe-finned fish

• Fleshy muscular pectoral and pelvic fins supported by bony elements in base

• Single basal skeletal bone + central supporting bones