Teaching and learning of invertebrate systematic require effective pedagogical language strategies since the terms used are most in English and Latin. The Tanzania education policy specifies that the medium language of instruction in primary must be Kiswahili, while English has to be used in post-primary education. Consequently, secondary school biology students find difficult to cope with learning in the context of foreign language. This paper aims at presenting the investigation on how pedagogical language strategies can effectively support teachers and learners during teaching and learning of systematic invertebrates in Tanzania secondary schools. Data were collected using the lesson observation checklist, lesson evaluation sheet, interview with teachers and focus group discussions with learners. A total of 60 sessions, each of 80 minutes were observed in 10 schools. A total of 40 teachers and 400 level four students of the ordinary level participated in the study. Quantitatively, paired sample t-test, means, standard deviations and percentages were used to evaluate and compare changes in learners' performance in pre- and post-tests. Further, thematic analysis was employed to analyse qualitative data. Key findings from the study indicated that the majority of teachers who participated in the training managed to set competencies and the activities to reinforce the achievements of developed competencies. Again, teachers and learners had a progressive significant improvement over introduced pedagogical language strategies. Overall, there was a statistically significant difference between pre- and post- intervention. Interviews with teachers and focus group discussions with students revealed that the strategies increased students' interactions and activeness in class, which in turn, improved the learning of biology content through the English language. This study therefore recommends the pedagogical language strategies to be adopted during teaching and learning of biology, specifically the content of invertebrate systematic.